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SQL Exercises: Employees whose department is in London

SQL SUBQUERY: Exercise-46 with Solution

From the following tables, write a SQL query to find all employees whose department is located in London. Return first name, last name, salary, and department ID.

Sample table: employees
+-------------+-------------+-------------+----------+--------------------+------------+------------+----------+----------------+------------+---------------+
| EMPLOYEE_ID | FIRST_NAME  | LAST_NAME   | EMAIL    | PHONE_NUMBER       | HIRE_DATE  | JOB_ID     | SALARY   | COMMISSION_PCT | MANAGER_ID | DEPARTMENT_ID |
+-------------+-------------+-------------+----------+--------------------+------------+------------+----------+----------------+------------+---------------+
|         100 | Steven      | King        | SKING    | 515.123.4567       | 2003-06-17 | AD_PRES    | 24000.00 |           0.00 |          0 |            90 |
|         101 | Neena       | Kochhar     | NKOCHHAR | 515.123.4568       | 2005-09-21 | AD_VP      | 17000.00 |           0.00 |        100 |            90 |
|         102 | Lex         | De Haan     | LDEHAAN  | 515.123.4569       | 2001-01-13 | AD_VP      | 17000.00 |           0.00 |        100 |            90 |
|         103 | Alexander   | Hunold      | AHUNOLD  | 590.423.4567       | 2006-01-03 | IT_PROG    |  9000.00 |           0.00 |        102 |            60 |
|         104 | Bruce       | Ernst       | BERNST   | 590.423.4568       | 2007-05-21 | IT_PROG    |  6000.00 |           0.00 |        103 |            60 |
|         105 | David       | Austin      | DAUSTIN  | 590.423.4569       | 2005-06-25 | IT_PROG    |  4800.00 |           0.00 |        103 |            60 |
|         106 | Valli       | Pataballa   | VPATABAL | 590.423.4560       | 2006-02-05 | IT_PROG    |  4800.00 |           0.00 |        103 |            60 |
|         107 | Diana       | Lorentz     | DLORENTZ | 590.423.5567       | 2007-02-07 | IT_PROG    |  4200.00 |           0.00 |        103 |            60 |
|         108 | Nancy       | Greenberg   | NGREENBE | 515.124.4569       | 2002-08-17 | FI_MGR     | 12008.00 |           0.00 |        101 |           100 |
|         109 | Daniel      | Faviet      | DFAVIET  | 515.124.4169       | 2002-08-16 | FI_ACCOUNT |  9000.00 |           0.00 |        108 |           100 |
|         110 | John        | Chen        | JCHEN    | 515.124.4269       | 2005-09-28 | FI_ACCOUNT |  8200.00 |           0.00 |        108 |           100 |
|         111 | Ismael      | Sciarra     | ISCIARRA | 515.124.4369       | 2005-09-30 | FI_ACCOUNT |  7700.00 |           0.00 |        108 |           100 |
|         112 | Jose Manuel | Urman       | JMURMAN  | 515.124.4469       | 2006-03-07 | FI_ACCOUNT |  7800.00 |           0.00 |        108 |           100 |
|         113 | Luis        | Popp        | LPOPP    | 515.124.4567       | 2007-12-07 | FI_ACCOUNT |  6900.00 |           0.00 |        108 |           100 |
|         114 | Den         | Raphaely    | DRAPHEAL | 515.127.4561       | 2002-12-07 | PU_MAN     | 11000.00 |           0.00 |        100 |            30 |
|         115 | Alexander   | Khoo        | AKHOO    | 515.127.4562       | 2003-05-18 | PU_CLERK   |  3100.00 |           0.00 |        114 |            30 |
|         116 | Shelli      | Baida       | SBAIDA   | 515.127.4563       | 2005-12-24 | PU_CLERK   |  2900.00 |           0.00 |        114 |            30 |
|         117 | Sigal       | Tobias      | STOBIAS  | 515.127.4564       | 2005-07-24 | PU_CLERK   |  2800.00 |           0.00 |        114 |            30 |
|         118 | Guy         | Himuro      | GHIMURO  | 515.127.4565       | 2006-11-15 | PU_CLERK   |  2600.00 |           0.00 |        114 |            30 |
|         119 | Karen       | Colmenares  | KCOLMENA | 515.127.4566       | 2007-08-10 | PU_CLERK   |  2500.00 |           0.00 |        114 |            30 |
|         120 | Matthew     | Weiss       | MWEISS   | 650.123.1234       | 2004-07-18 | ST_MAN     |  8000.00 |           0.00 |        100 |            50 |
|         121 | Adam        | Fripp       | AFRIPP   | 650.123.2234       | 2005-04-10 | ST_MAN     |  8200.00 |           0.00 |        100 |            50 |
|         122 | Payam       | Kaufling    | PKAUFLIN | 650.123.3234       | 2003-05-01 | ST_MAN     |  7900.00 |           0.00 |        100 |            50 |
|         123 | Shanta      | Vollman     | SVOLLMAN | 650.123.4234       | 2005-10-10 | ST_MAN     |  6500.00 |           0.00 |        100 |            50 |
|         124 | Kevin       | Mourgos     | KMOURGOS | 650.123.5234       | 2007-11-16 | ST_MAN     |  5800.00 |           0.00 |        100 |            50 |
|         125 | Julia       | Nayer       | JNAYER   | 650.124.1214       | 2005-07-16 | ST_CLERK   |  3200.00 |           0.00 |        120 |            50 |
|         126 | Irene       | Mikkilineni | IMIKKILI | 650.124.1224       | 2006-09-28 | ST_CLERK   |  2700.00 |           0.00 |        120 |            50 |
|         127 | James       | Landry      | JLANDRY  | 650.124.1334       | 2007-01-14 | ST_CLERK   |  2400.00 |           0.00 |        120 |            50 |
|         128 | Steven      | Markle      | SMARKLE  | 650.124.1434       | 2008-03-08 | ST_CLERK   |  2200.00 |           0.00 |        120 |            50 |
|         129 | Laura       | Bissot      | LBISSOT  | 650.124.5234       | 2005-08-20 | ST_CLERK   |  3300.00 |           0.00 |        121 |            50 |
|         130 | Mozhe       | Atkinson    | MATKINSO | 650.124.6234       | 2005-10-30 | ST_CLERK   |  2800.00 |           0.00 |        121 |            50 |
|         131 | James       | Marlow      | JAMRLOW  | 650.124.7234       | 2005-02-16 | ST_CLERK   |  2500.00 |           0.00 |        121 |            50 |
|         132 | TJ          | Olson       | TJOLSON  | 650.124.8234       | 2007-04-10 | ST_CLERK   |  2100.00 |           0.00 |        121 |            50 |
|         133 | Jason       | Mallin      | JMALLIN  | 650.127.1934       | 2004-06-14 | ST_CLERK   |  3300.00 |           0.00 |        122 |            50 |
|         134 | Michael     | Rogers      | MROGERS  | 650.127.1834       | 2006-08-26 | ST_CLERK   |  2900.00 |           0.00 |        122 |            50 |
|         135 | Ki          | Gee         | KGEE     | 650.127.1734       | 2007-12-12 | ST_CLERK   |  2400.00 |           0.00 |        122 |            50 |
|         136 | Hazel       | Philtanker  | HPHILTAN | 650.127.1634       | 2008-02-06 | ST_CLERK   |  2200.00 |           0.00 |        122 |            50 |
|         137 | Renske      | Ladwig      | RLADWIG  | 650.121.1234       | 2003-07-14 | ST_CLERK   |  3600.00 |           0.00 |        123 |            50 |
|         138 | Stephen     | Stiles      | SSTILES  | 650.121.2034       | 2005-10-26 | ST_CLERK   |  3200.00 |           0.00 |        123 |            50 |
|         139 | John        | Seo         | JSEO     | 650.121.2019       | 2006-02-12 | ST_CLERK   |  2700.00 |           0.00 |        123 |            50 |
|         140 | Joshua      | Patel       | JPATEL   | 650.121.1834       | 2006-04-06 | ST_CLERK   |  2500.00 |           0.00 |        123 |            50 |
|         141 | Trenna      | Rajs        | TRAJS    | 650.121.8009       | 2003-10-17 | ST_CLERK   |  3500.00 |           0.00 |        124 |            50 |
|         142 | Curtis      | Davies      | CDAVIES  | 650.121.2994       | 2005-01-29 | ST_CLERK   |  3100.00 |           0.00 |        124 |            50 |
|         143 | Randall     | Matos       | RMATOS   | 650.121.2874       | 2006-03-15 | ST_CLERK   |  2600.00 |           0.00 |        124 |            50 |
|         144 | Peter       | Vargas      | PVARGAS  | 650.121.2004       | 2006-07-09 | ST_CLERK   |  2500.00 |           0.00 |        124 |            50 |
|         145 | John        | Russell     | JRUSSEL  | 011.44.1344.429268 | 2004-10-01 | SA_MAN     | 14000.00 |           0.40 |        100 |            80 |
|         146 | Karen       | Partners    | KPARTNER | 011.44.1344.467268 | 2005-01-05 | SA_MAN     | 13500.00 |           0.30 |        100 |            80 |
|         147 | Alberto     | Errazuriz   | AERRAZUR | 011.44.1344.429278 | 2005-03-10 | SA_MAN     | 12000.00 |           0.30 |        100 |            80 |
|         148 | Gerald      | Cambrault   | GCAMBRAU | 011.44.1344.619268 | 2007-10-15 | SA_MAN     | 11000.00 |           0.30 |        100 |            80 |
|         149 | Eleni       | Zlotkey     | EZLOTKEY | 011.44.1344.429018 | 2008-01-29 | SA_MAN     | 10500.00 |           0.20 |        100 |            80 |
|         150 | Peter       | Tucker      | PTUCKER  | 011.44.1344.129268 | 2005-01-30 | SA_REP     | 10000.00 |           0.30 |        145 |            80 |
|         151 | David       | Bernstein   | DBERNSTE | 011.44.1344.345268 | 2005-03-24 | SA_REP     |  9500.00 |           0.25 |        145 |            80 |
|         152 | Peter       | Hall        | PHALL    | 011.44.1344.478968 | 2005-08-20 | SA_REP     |  9000.00 |           0.25 |        145 |            80 |
|         153 | Christopher | Olsen       | COLSEN   | 011.44.1344.498718 | 2006-03-30 | SA_REP     |  8000.00 |           0.20 |        145 |            80 |
|         154 | Nanette     | Cambrault   | NCAMBRAU | 011.44.1344.987668 | 2006-12-09 | SA_REP     |  7500.00 |           0.20 |        145 |            80 |
|         155 | Oliver      | Tuvault     | OTUVAULT | 011.44.1344.486508 | 2007-11-23 | SA_REP     |  7000.00 |           0.15 |        145 |            80 |
|         156 | Janette     | King        | JKING    | 011.44.1345.429268 | 2004-01-30 | SA_REP     | 10000.00 |           0.35 |        146 |            80 |
|         157 | Patrick     | Sully       | PSULLY   | 011.44.1345.929268 | 2004-03-04 | SA_REP     |  9500.00 |           0.35 |        146 |            80 |
|         158 | Allan       | McEwen      | AMCEWEN  | 011.44.1345.829268 | 2004-08-01 | SA_REP     |  9000.00 |           0.35 |        146 |            80 |
|         159 | Lindsey     | Smith       | LSMITH   | 011.44.1345.729268 | 2005-03-10 | SA_REP     |  8000.00 |           0.30 |        146 |            80 |
|         160 | Louise      | Doran       | LDORAN   | 011.44.1345.629268 | 2005-12-15 | SA_REP     |  7500.00 |           0.30 |        146 |            80 |
|         161 | Sarath      | Sewall      | SSEWALL  | 011.44.1345.529268 | 2006-11-03 | SA_REP     |  7000.00 |           0.25 |        146 |            80 |
|         162 | Clara       | Vishney     | CVISHNEY | 011.44.1346.129268 | 2005-11-11 | SA_REP     | 10500.00 |           0.25 |        147 |            80 |
|         163 | Danielle    | Greene      | DGREENE  | 011.44.1346.229268 | 2007-03-19 | SA_REP     |  9500.00 |           0.15 |        147 |            80 |
|         164 | Mattea      | Marvins     | MMARVINS | 011.44.1346.329268 | 2008-01-24 | SA_REP     |  7200.00 |           0.10 |        147 |            80 |
|         165 | David       | Lee         | DLEE     | 011.44.1346.529268 | 2008-02-23 | SA_REP     |  6800.00 |           0.10 |        147 |            80 |
|         166 | Sundar      | Ande        | SANDE    | 011.44.1346.629268 | 2008-03-24 | SA_REP     |  6400.00 |           0.10 |        147 |            80 |
|         167 | Amit        | Banda       | ABANDA   | 011.44.1346.729268 | 2008-04-21 | SA_REP     |  6200.00 |           0.10 |        147 |            80 |
|         168 | Lisa        | Ozer        | LOZER    | 011.44.1343.929268 | 2005-03-11 | SA_REP     | 11500.00 |           0.25 |        148 |            80 |
|         169 | Harrison    | Bloom       | HBLOOM   | 011.44.1343.829268 | 2006-03-23 | SA_REP     | 10000.00 |           0.20 |        148 |            80 |
|         170 | Tayler      | Fox         | TFOX     | 011.44.1343.729268 | 2006-01-24 | SA_REP     |  9600.00 |           0.20 |        148 |            80 |
|         171 | William     | Smith       | WSMITH   | 011.44.1343.629268 | 2007-02-23 | SA_REP     |  7400.00 |           0.15 |        148 |            80 |
|         172 | Elizabeth   | Bates       | EBATES   | 011.44.1343.529268 | 2007-03-24 | SA_REP     |  7300.00 |           0.15 |        148 |            80 |
|         173 | Sundita     | Kumar       | SKUMAR   | 011.44.1343.329268 | 2008-04-21 | SA_REP     |  6100.00 |           0.10 |        148 |            80 |
|         174 | Ellen       | Abel        | EABEL    | 011.44.1644.429267 | 2004-05-11 | SA_REP     | 11000.00 |           0.30 |        149 |            80 |
|         175 | Alyssa      | Hutton      | AHUTTON  | 011.44.1644.429266 | 2005-03-19 | SA_REP     |  8800.00 |           0.25 |        149 |            80 |
|         176 | Jonathon    | Taylor      | JTAYLOR  | 011.44.1644.429265 | 2006-03-24 | SA_REP     |  8600.00 |           0.20 |        149 |            80 |
|         177 | Jack        | Livingston  | JLIVINGS | 011.44.1644.429264 | 2006-04-23 | SA_REP     |  8400.00 |           0.20 |        149 |            80 |
|         178 | Kimberely   | Grant       | KGRANT   | 011.44.1644.429263 | 2007-05-24 | SA_REP     |  7000.00 |           0.15 |        149 |             0 |
|         179 | Charles     | Johnson     | CJOHNSON | 011.44.1644.429262 | 2008-01-04 | SA_REP     |  6200.00 |           0.10 |        149 |            80 |
|         180 | Winston     | Taylor      | WTAYLOR  | 650.507.9876       | 2006-01-24 | SH_CLERK   |  3200.00 |           0.00 |        120 |            50 |
|         181 | Jean        | Fleaur      | JFLEAUR  | 650.507.9877       | 2006-02-23 | SH_CLERK   |  3100.00 |           0.00 |        120 |            50 |
|         182 | Martha      | Sullivan    | MSULLIVA | 650.507.9878       | 2007-06-21 | SH_CLERK   |  2500.00 |           0.00 |        120 |            50 |
|         183 | Girard      | Geoni       | GGEONI   | 650.507.9879       | 2008-02-03 | SH_CLERK   |  2800.00 |           0.00 |        120 |            50 |
|         184 | Nandita     | Sarchand    | NSARCHAN | 650.509.1876       | 2004-01-27 | SH_CLERK   |  4200.00 |           0.00 |        121 |            50 |
|         185 | Alexis      | Bull        | ABULL    | 650.509.2876       | 2005-02-20 | SH_CLERK   |  4100.00 |           0.00 |        121 |            50 |
|         186 | Julia       | Dellinger   | JDELLING | 650.509.3876       | 2006-06-24 | SH_CLERK   |  3400.00 |           0.00 |        121 |            50 |
|         187 | Anthony     | Cabrio      | ACABRIO  | 650.509.4876       | 2007-02-07 | SH_CLERK   |  3000.00 |           0.00 |        121 |            50 |
|         188 | Kelly       | Chung       | KCHUNG   | 650.505.1876       | 2005-06-14 | SH_CLERK   |  3800.00 |           0.00 |        122 |            50 |
|         189 | Jennifer    | Dilly       | JDILLY   | 650.505.2876       | 2005-08-13 | SH_CLERK   |  3600.00 |           0.00 |        122 |            50 |
|         190 | Timothy     | Gates       | TGATES   | 650.505.3876       | 2006-07-11 | SH_CLERK   |  2900.00 |           0.00 |        122 |            50 |
|         191 | Randall     | Perkins     | RPERKINS | 650.505.4876       | 2007-12-19 | SH_CLERK   |  2500.00 |           0.00 |        122 |            50 |
|         192 | Sarah       | Bell        | SBELL    | 650.501.1876       | 2004-02-04 | SH_CLERK   |  4000.00 |           0.00 |        123 |            50 |
|         193 | Britney     | Everett     | BEVERETT | 650.501.2876       | 2005-03-03 | SH_CLERK   |  3900.00 |           0.00 |        123 |            50 |
|         194 | Samuel      | McCain      | SMCCAIN  | 650.501.3876       | 2006-07-01 | SH_CLERK   |  3200.00 |           0.00 |        123 |            50 |
|         195 | Vance       | Jones       | VJONES   | 650.501.4876       | 2007-03-17 | SH_CLERK   |  2800.00 |           0.00 |        123 |            50 |
|         196 | Alana       | Walsh       | AWALSH   | 650.507.9811       | 2006-04-24 | SH_CLERK   |  3100.00 |           0.00 |        124 |            50 |
|         197 | Kevin       | Feeney      | KFEENEY  | 650.507.9822       | 2006-05-23 | SH_CLERK   |  3000.00 |           0.00 |        124 |            50 |
|         198 | Donald      | OConnell    | DOCONNEL | 650.507.9833       | 2007-06-21 | SH_CLERK   |  2600.00 |           0.00 |        124 |            50 |
|         199 | Douglas     | Grant       | DGRANT   | 650.507.9844       | 2008-01-13 | SH_CLERK   |  2600.00 |           0.00 |        124 |            50 |
|         200 | Jennifer    | Whalen      | JWHALEN  | 515.123.4444       | 2003-09-17 | AD_ASST    |  4400.00 |           0.00 |        101 |            10 |
|         201 | Michael     | Hartstein   | MHARTSTE | 515.123.5555       | 2004-02-17 | MK_MAN     | 13000.00 |           0.00 |        100 |            20 |
|         202 | Pat         | Fay         | PFAY     | 603.123.6666       | 2005-08-17 | MK_REP     |  6000.00 |           0.00 |        201 |            20 |
|         203 | Susan       | Mavris      | SMAVRIS  | 515.123.7777       | 2002-06-07 | HR_REP     |  6500.00 |           0.00 |        101 |            40 |
|         204 | Hermann     | Baer        | HBAER    | 515.123.8888       | 2002-06-07 | PR_REP     | 10000.00 |           0.00 |        101 |            70 |
|         205 | Shelley     | Higgins     | SHIGGINS | 515.123.8080       | 2002-06-07 | AC_MGR     | 12008.00 |           0.00 |        101 |           110 |
|         206 | William     | Gietz       | WGIETZ   | 515.123.8181       | 2002-06-07 | AC_ACCOUNT |  8300.00 |           0.00 |        205 |           110 |
+-------------+-------------+-------------+----------+--------------------+------------+------------+----------+----------------+------------+---------------+
Sample table: locations
+-------------+------------------------------------------+-------------+---------------------+-------------------+------------+
| LOCATION_ID | STREET_ADDRESS                           | POSTAL_CODE | CITY                | STATE_PROVINCE    | COUNTRY_ID |
+-------------+------------------------------------------+-------------+---------------------+-------------------+------------+
|        1000 | 1297 Via Cola di Rie                     | 989         | Roma                |                   | IT         |
|        1100 | 93091 Calle della Testa                  | 10934       | Venice              |                   | IT         |
|        1200 | 2017 Shinjuku-ku                         | 1689        | Tokyo               | Tokyo Prefecture  | JP         |
|        1300 | 9450 Kamiya-cho                          | 6823        | Hiroshima           |                   | JP         |
|        1400 | 2014 Jabberwocky Rd                      | 26192       | Southlake           | Texas             | US         |
|        1500 | 2011 Interiors Blvd                      | 99236       | South San Francisco | California        | US         |
|        1600 | 2007 Zagora St                           | 50090       | South Brunswick     | New Jersey        | US         |
|        1700 | 2004 Charade Rd                          | 98199       | Seattle             | Washington        | US         |
|        1800 | 147 Spadina Ave                          | M5V 2L7     | Toronto             | Ontario           | CA         |
|        1900 | 6092 Boxwood St                          | YSW 9T2     | Whitehorse          | Yukon             | CA         |
|        2000 | 40-5-12 Laogianggen                      | 190518      | Beijing             |                   | CN         |
|        2100 | 1298 Vileparle (E)                       | 490231      | Bombay              | Maharashtra       | IN         |
|        2200 | 12-98 Victoria Street                    | 2901        | Sydney              | New South Wales   | AU         |
|        2300 | 198 Clementi North                       | 540198      | Singapore           |                   | SG         |
|        2400 | 8204 Arthur St                           |             | London              |                   | UK         |
|        2500 | Magdalen Centre, The Oxford Science Park | OX9 9ZB     | Oxford              | Oxford            | UK         |
|        2600 | 9702 Chester Road                        | 9629850293  | Stretford           | Manchester        | UK         |
|        2700 | Schwanthalerstr. 7031                    | 80925       | Munich              | Bavaria           | DE         |
|        2800 | Rua Frei Caneca 1360                     | 01307-002   | Sao Paulo           | Sao Paulo         | BR         |
|        2900 | 20 Rue des Corps-Saints                  | 1730        | Geneva              | Geneve            | CH         |
|        3000 | Murtenstrasse 921                        | 3095        | Bern                | BE                | CH         |
|        3100 | Pieter Breughelstraat 837                | 3029SK      | Utrecht             | Utrecht           | NL         |
|        3200 | Mariano Escobedo 9991                    | 11932       | Mexico City         | Distrito Federal, | MX         |
+-------------+------------------------------------------+-------------+---------------------+-------------------+------------+
Sample table: departments
+---------------+----------------------+------------+-------------+
| DEPARTMENT_ID | DEPARTMENT_NAME      | MANAGER_ID | LOCATION_ID |
+---------------+----------------------+------------+-------------+
|            10 | Administration       |        200 |        1700 |
|            20 | Marketing            |        201 |        1800 |
|            30 | Purchasing           |        114 |        1700 |
|            40 | Human Resources      |        203 |        2400 |
|            50 | Shipping             |        121 |        1500 |
|            60 | IT                   |        103 |        1400 |
|            70 | Public Relations     |        204 |        2700 |
|            80 | Sales                |        145 |        2500 |
|            90 | Executive            |        100 |        1700 |
|           100 | Finance              |        108 |        1700 |
|           110 | Accounting           |        205 |        1700 |
|           120 | Treasury             |          0 |        1700 |
|           130 | Corporate Tax        |          0 |        1700 |
|           140 | Control And Credit   |          0 |        1700 |
|           150 | Shareholder Services |          0 |        1700 |
|           160 | Benefits             |          0 |        1700 |
|           170 | Manufacturing        |          0 |        1700 |
|           180 | Construction         |          0 |        1700 |
|           190 | Contracting          |          0 |        1700 |
|           200 | Operations           |          0 |        1700 |
|           210 | IT Support           |          0 |        1700 |
|           220 | NOC                  |          0 |        1700 |
|           230 | IT Helpdesk          |          0 |        1700 |
|           240 | Government Sales     |          0 |        1700 |
|           250 | Retail Sales         |          0 |        1700 |
|           260 | Recruiting           |          0 |        1700 |
|           270 | Payroll              |          0 |        1700 |
+---------------+----------------------+------------+-------------+

Sample Solution:

-- Selecting specific columns (first_name, last_name, salary, department_id) from the 'employees' table
SELECT first_name, last_name, salary, department_id 

-- Filtering rows based on the condition that the 'department_id' is in the result set of a nested subquery
FROM employees

-- Subquery to find 'department_id' values where the 'location_id' matches the result of another subquery
WHERE department_id IN 
          (SELECT department_id 
            FROM departments 

            -- Subquery to find 'location_id' values where the 'city' is 'London' in the 'locations' table
            WHERE location_id = 
               (SELECT location_id 
                 FROM locations 

                 -- Condition to find 'location_id' values where the 'city' is 'London'
                   WHERE city = 'London')
          );

Sample Output:

first_name	last_name	salary	department_id
Susan		Mavris		6500.00	40

Code Explanation:

The said query in SQL that retrieves data from the 'employees' table. The columns selected are "first_name", "last_name", "salary", and "department_id". The query only returns rows where the department_id of the employees is in a list of department_id's from departments located in London.
The subquery in the WHERE clause first selects the location_id of the city 'London' from the 'locations' table. This result is then used in another subquery to select the department_id of departments located in London from the 'departments' table.

Visual Presentation:

SQL Subqueries Exercises: Display the first and last name, salary and department ID for those employees whose department is located in the city London.

Alternative Solutions:

Using JOINs:


SELECT e.first_name, e.last_name, e.salary, e.department_id 
FROM employees e
JOIN departments d ON e.department_id = d.department_id
JOIN locations l ON d.location_id = l.location_id
WHERE l.city = 'London';

Using EXISTS:


SELECT first_name, last_name, salary, department_id 
FROM employees e1
WHERE EXISTS (
    SELECT 1
    FROM departments d 
    JOIN locations l ON d.location_id = l.location_id
    WHERE d.department_id = e1.department_id AND l.city = 'London'
);

Using JOINs and Subqueries:


SELECT e.first_name, e.last_name, e.salary, e.department_id 
FROM employees e
JOIN (
    SELECT department_id 
    FROM departments 
    WHERE location_id = (
        SELECT location_id 
        FROM locations 
        WHERE city = 'London'
    )
) d ON e.department_id = d.department_id;

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Query Visualization:

Duration:

Query visualization of Display the first and last name, salary and department ID for those employees whose department is located in the city London - Duration

Rows:

Query visualization of Display the first and last name, salary and department ID for those employees whose department is located in the city London - Rows

Cost:

Query visualization of Display the first and last name, salary and department ID for those employees whose department is located in the city London - Cost

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