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SQLite Exercise: Find the names of the employees who have a manager who works for a department based in the United States

Write a query to find the names (first_name, last_name) of the employees who have a manager who works for a department based in the United States.

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       | 1987-06-17 | AD_PRES    | 24000.00 |           0.00 |          0 | 		  90 |
|         101 | Neena       | Kochhar     | NKOCHHAR | 515.123.4568       | 1987-06-18 | AD_VP      | 17000.00 |           0.00 |        100 |            90 |
|         102 | Lex         | De Haan     | LDEHAAN  | 515.123.4569       | 1987-06-19 | AD_VP      | 17000.00 |           0.00 |        100 |            90 |
|         103 | Alexander   | Hunold      | AHUNOLD  | 590.423.4567       | 1987-06-20 | IT_PROG    |  9000.00 |           0.00 |        102 |            60 |
|         104 | Bruce       | Ernst       | BERNST   | 590.423.4568       | 1987-06-21 | IT_PROG    |  6000.00 |           0.00 |        103 |            60 |
|         105 | David       | Austin      | DAUSTIN  | 590.423.4569       | 1987-06-22 | IT_PROG    |  4800.00 |           0.00 |        103 |            60 |
|         106 | Valli       | Pataballa   | VPATABAL | 590.423.4560       | 1987-06-23 | IT_PROG    |  4800.00 |           0.00 |        103 |            60 |
|         107 | Diana       | Lorentz     | DLORENTZ | 590.423.5567       | 1987-06-24 | IT_PROG    |  4200.00 |           0.00 |        103 |            60 |
|         108 | Nancy       | Greenberg   | NGREENBE | 515.124.4569       | 1987-06-25 | FI_MGR     | 12000.00 |           0.00 |        101 |           100 |
|         109 | Daniel      | Faviet      | DFAVIET  | 515.124.4169       | 1987-06-26 | FI_ACCOUNT |  9000.00 |           0.00 |        108 |           100 |
|         110 | John        | Chen        | JCHEN    | 515.124.4269       | 1987-06-27 | FI_ACCOUNT |  8200.00 |           0.00 |        108 |           100 |
|         111 | Ismael      | Sciarra     | ISCIARRA | 515.124.4369       | 1987-06-28 | FI_ACCOUNT |  7700.00 |           0.00 |        108 |           100 |
|         112 | Jose Manuel | Urman       | JMURMAN  | 515.124.4469       | 1987-06-29 | FI_ACCOUNT |  7800.00 |           0.00 |        108 |           100 |
|         113 | Luis        | Popp        | LPOPP    | 515.124.4567       | 1987-06-30 | FI_ACCOUNT |  6900.00 |           0.00 |        108 |           100 |
|         114 | Den         | Raphaely    | DRAPHEAL | 515.127.4561       | 1987-07-01 | PU_MAN     | 11000.00 |           0.00 |        100 |            30 |
|         115 | Alexander   | Khoo        | AKHOO    | 515.127.4562       | 1987-07-02 | PU_CLERK   |  3100.00 |           0.00 |        114 |            30 |
|         116 | Shelli      | Baida       | SBAIDA   | 515.127.4563       | 1987-07-03 | PU_CLERK   |  2900.00 |           0.00 |        114 |            30 |
|         117 | Sigal       | Tobias      | STOBIAS  | 515.127.4564       | 1987-07-04 | PU_CLERK   |  2800.00 |           0.00 |        114 |            30 |
|         118 | Guy         | Himuro      | GHIMURO  | 515.127.4565       | 1987-07-05 | PU_CLERK   |  2600.00 |           0.00 |        114 |            30 |
|         119 | Karen       | Colmenares  | KCOLMENA | 515.127.4566       | 1987-07-06 | PU_CLERK   |  2500.00 |           0.00 |        114 |            30 |
|         120 | Matthew     | Weiss       | MWEISS   | 650.123.1234       | 1987-07-07 | ST_MAN     |  8000.00 |           0.00 |        100 |            50 |
|         121 | Adam        | Fripp       | AFRIPP   | 650.123.2234       | 1987-07-08 | ST_MAN     |  8200.00 |           0.00 |        100 |            50 |
|         122 | Payam       | Kaufling    | PKAUFLIN | 650.123.3234       | 1987-07-09 | ST_MAN     |  7900.00 |           0.00 |        100 |            50 |
|         123 | Shanta      | Vollman     | SVOLLMAN | 650.123.4234       | 1987-07-10 | ST_MAN     |  6500.00 |           0.00 |        100 |            50 |
|         124 | Kevin       | Mourgos     | KMOURGOS | 650.123.5234       | 1987-07-11 | ST_MAN     |  5800.00 |           0.00 |        100 |            50 |
|         125 | Julia       | Nayer       | JNAYER   | 650.124.1214       | 1987-07-12 | ST_CLERK   |  3200.00 |           0.00 |        120 |            50 |
|         126 | Irene       | Mikkilineni | IMIKKILI | 650.124.1224       | 1987-07-13 | ST_CLERK   |  2700.00 |           0.00 |        120 |            50 |
|         127 | James       | Landry      | JLANDRY  | 650.124.1334       | 1987-07-14 | ST_CLERK   |  2400.00 |           0.00 |        120 |            50 |
|         128 | Steven      | Markle      | SMARKLE  | 650.124.1434       | 1987-07-15 | ST_CLERK   |  2200.00 |           0.00 |        120 |            50 |
|         129 | Laura       | Bissot      | LBISSOT  | 650.124.5234       | 1987-07-16 | ST_CLERK   |  3300.00 |           0.00 |        121 |            50 |
|         130 | Mozhe       | Atkinson    | MATKINSO | 650.124.6234       | 1987-07-17 | ST_CLERK   |  2800.00 |           0.00 |        121 |            50 |
|         131 | James       | Marlow      | JAMRLOW  | 650.124.7234       | 1987-07-18 | ST_CLERK   |  2500.00 |           0.00 |        121 |            50 |
|         132 | TJ          | Olson       | TJOLSON  | 650.124.8234       | 1987-07-19 | ST_CLERK   |  2100.00 |           0.00 |        121 |            50 |
|         133 | Jason       | Mallin      | JMALLIN  | 650.127.1934       | 1987-07-20 | ST_CLERK   |  3300.00 |           0.00 |        122 |            50 |
|         134 | Michael     | Rogers      | MROGERS  | 650.127.1834       | 1987-07-21 | ST_CLERK   |  2900.00 |           0.00 |        122 |            50 |
|         135 | Ki          | Gee         | KGEE     | 650.127.1734       | 1987-07-22 | ST_CLERK   |  2400.00 |           0.00 |        122 |            50 |
|         136 | Hazel       | Philtanker  | HPHILTAN | 650.127.1634       | 1987-07-23 | ST_CLERK   |  2200.00 |           0.00 |        122 |            50 |
|         137 | Renske      | Ladwig      | RLADWIG  | 650.121.1234       | 1987-07-24 | ST_CLERK   |  3600.00 |           0.00 |        123 |            50 |
|         138 | Stephen     | Stiles      | SSTILES  | 650.121.2034       | 1987-07-25 | ST_CLERK   |  3200.00 |           0.00 |        123 |            50 |
|         139 | John        | Seo         | JSEO     | 650.121.2019       | 1987-07-26 | ST_CLERK   |  2700.00 |           0.00 |        123 |            50 |
|         140 | Joshua      | Patel       | JPATEL   | 650.121.1834       | 1987-07-27 | ST_CLERK   |  2500.00 |           0.00 |        123 |            50 |
|         141 | Trenna      | Rajs        | TRAJS    | 650.121.8009       | 1987-07-28 | ST_CLERK   |  3500.00 |           0.00 |        124 |            50 |
|         142 | Curtis      | Davies      | CDAVIES  | 650.121.2994       | 1987-07-29 | ST_CLERK   |  3100.00 |           0.00 |        124 |            50 |
|         143 | Randall     | Matos       | RMATOS   | 650.121.2874       | 1987-07-30 | ST_CLERK   |  2600.00 |           0.00 |        124 |            50 |
|         144 | Peter       | Vargas      | PVARGAS  | 650.121.2004       | 1987-07-31 | ST_CLERK   |  2500.00 |           0.00 |        124 |            50 |
|         145 | John        | Russell     | JRUSSEL  | 011.44.1344.429268 | 1987-08-01 | SA_MAN     | 14000.00 |           0.40 |        100 |            80 |
|         146 | Karen       | Partners    | KPARTNER | 011.44.1344.467268 | 1987-08-02 | SA_MAN     | 13500.00 |           0.30 |        100 |            80 |
|         147 | Alberto     | Errazuriz   | AERRAZUR | 011.44.1344.429278 | 1987-08-03 | SA_MAN     | 12000.00 |           0.30 |        100 |            80 |
|         148 | Gerald      | Cambrault   | GCAMBRAU | 011.44.1344.619268 | 1987-08-04 | SA_MAN     | 11000.00 |           0.30 |        100 |            80 |
|         149 | Eleni       | Zlotkey     | EZLOTKEY | 011.44.1344.429018 | 1987-08-05 | SA_MAN     | 10500.00 |           0.20 |        100 |            80 |
|         150 | Peter       | Tucker      | PTUCKER  | 011.44.1344.129268 | 1987-08-06 | SA_REP     | 10000.00 |           0.30 |        145 |            80 |
|         151 | David       | Bernstein   | DBERNSTE | 011.44.1344.345268 | 1987-08-07 | SA_REP     |  9500.00 |           0.25 |        145 |            80 |
|         152 | Peter       | Hall        | PHALL    | 011.44.1344.478968 | 1987-08-08 | SA_REP     |  9000.00 |           0.25 |        145 |            80 |
|         153 | Christopher | Olsen       | COLSEN   | 011.44.1344.498718 | 1987-08-09 | SA_REP     |  8000.00 |           0.20 |        145 |            80 |
|         154 | Nanette     | Cambrault   | NCAMBRAU | 011.44.1344.987668 | 1987-08-10 | SA_REP     |  7500.00 |           0.20 |        145 |            80 |
|         155 | Oliver      | Tuvault     | OTUVAULT | 011.44.1344.486508 | 1987-08-11 | SA_REP     |  7000.00 |           0.15 |        145 |            80 |
|         156 | Janette     | King        | JKING    | 011.44.1345.429268 | 1987-08-12 | SA_REP     | 10000.00 |           0.35 |        146 |            80 |
|         157 | Patrick     | Sully       | PSULLY   | 011.44.1345.929268 | 1987-08-13 | SA_REP     |  9500.00 |           0.35 |        146 |            80 |
|         158 | Allan       | McEwen      | AMCEWEN  | 011.44.1345.829268 | 1987-08-14 | SA_REP     |  9000.00 |           0.35 |        146 |            80 |
|         159 | Lindsey     | Smith       | LSMITH   | 011.44.1345.729268 | 1987-08-15 | SA_REP     |  8000.00 |           0.30 |        146 |            80 |
|         160 | Louise      | Doran       | LDORAN   | 011.44.1345.629268 | 1987-08-16 | SA_REP     |  7500.00 |           0.30 |        146 |            80 |
|         161 | Sarath      | Sewall      | SSEWALL  | 011.44.1345.529268 | 1987-08-17 | SA_REP     |  7000.00 |           0.25 |        146 |            80 |
|         162 | Clara       | Vishney     | CVISHNEY | 011.44.1346.129268 | 1987-08-18 | SA_REP     | 10500.00 |           0.25 |        147 |            80 |
|         163 | Danielle    | Greene      | DGREENE  | 011.44.1346.229268 | 1987-08-19 | SA_REP     |  9500.00 |           0.15 |        147 |            80 |
|         164 | Mattea      | Marvins     | MMARVINS | 011.44.1346.329268 | 1987-08-20 | SA_REP     |  7200.00 |           0.10 |        147 |            80 |
|         165 | David       | Lee         | DLEE     | 011.44.1346.529268 | 1987-08-21 | SA_REP     |  6800.00 |           0.10 |        147 |            80 |
|         166 | Sundar      | Ande        | SANDE    | 011.44.1346.629268 | 1987-08-22 | SA_REP     |  6400.00 |           0.10 |        147 |            80 |
|         167 | Amit        | Banda       | ABANDA   | 011.44.1346.729268 | 1987-08-23 | SA_REP     |  6200.00 |           0.10 |        147 |            80 |
|         168 | Lisa        | Ozer        | LOZER    | 011.44.1343.929268 | 1987-08-24 | SA_REP     | 11500.00 |           0.25 |        148 |            80 |
|         169 | Harrison    | Bloom       | HBLOOM   | 011.44.1343.829268 | 1987-08-25 | SA_REP     | 10000.00 |           0.20 |        148 |            80 |
|         170 | Tayler      | Fox         | TFOX     | 011.44.1343.729268 | 1987-08-26 | SA_REP     |  9600.00 |           0.20 |        148 |            80 |
|         171 | William     | Smith       | WSMITH   | 011.44.1343.629268 | 1987-08-27 | SA_REP     |  7400.00 |           0.15 |        148 |            80 |
|         172 | Elizabeth   | Bates       | EBATES   | 011.44.1343.529268 | 1987-08-28 | SA_REP     |  7300.00 |           0.15 |        148 |            80 |
|         173 | Sundita     | Kumar       | SKUMAR   | 011.44.1343.329268 | 1987-08-29 | SA_REP     |  6100.00 |           0.10 |        148 |            80 |
|         174 | Ellen       | Abel        | EABEL    | 011.44.1644.429267 | 1987-08-30 | SA_REP     | 11000.00 |           0.30 |        149 |            80 |
|         175 | Alyssa      | Hutton      | AHUTTON  | 011.44.1644.429266 | 1987-08-31 | SA_REP     |  8800.00 |           0.25 |        149 |            80 |
|         176 | Jonathon    | Taylor      | JTAYLOR  | 011.44.1644.429265 | 1987-09-01 | SA_REP     |  8600.00 |           0.20 |        149 |            80 |
|         177 | Jack        | Livingston  | JLIVINGS | 011.44.1644.429264 | 1987-09-02 | SA_REP     |  8400.00 |           0.20 |        149 |            80 |
|         178 | Kimberely   | Grant       | KGRANT   | 011.44.1644.429263 | 1987-09-03 | SA_REP     |  7000.00 |           0.15 |        149 |             0 |
|         179 | Charles     | Johnson     | CJOHNSON | 011.44.1644.429262 | 1987-09-04 | SA_REP     |  6200.00 |           0.10 |        149 |            80 |
|         180 | Winston     | Taylor      | WTAYLOR  | 650.507.9876       | 1987-09-05 | SH_CLERK   |  3200.00 |           0.00 |        120 |            50 |
|         181 | Jean        | Fleaur      | JFLEAUR  | 650.507.9877       | 1987-09-06 | SH_CLERK   |  3100.00 |           0.00 |        120 |            50 |
|         182 | Martha      | Sullivan    | MSULLIVA | 650.507.9878       | 1987-09-07 | SH_CLERK   |  2500.00 |           0.00 |        120 |            50 |
|         183 | Girard      | Geoni       | GGEONI   | 650.507.9879       | 1987-09-08 | SH_CLERK   |  2800.00 |           0.00 |        120 |            50 |
|         184 | Nandita     | Sarchand    | NSARCHAN | 650.509.1876       | 1987-09-09 | SH_CLERK   |  4200.00 |           0.00 |        121 |            50 |
|         185 | Alexis      | Bull        | ABULL    | 650.509.2876       | 1987-09-10 | SH_CLERK   |  4100.00 |           0.00 |        121 |            50 |
|         186 | Julia       | Dellinger   | JDELLING | 650.509.3876       | 1987-09-11 | SH_CLERK   |  3400.00 |           0.00 |        121 |            50 |
|         187 | Anthony     | Cabrio      | ACABRIO  | 650.509.4876       | 1987-09-12 | SH_CLERK   |  3000.00 |           0.00 |        121 |            50 |
|         188 | Kelly       | Chung       | KCHUNG   | 650.505.1876       | 1987-09-13 | SH_CLERK   |  3800.00 |           0.00 |        122 |            50 |
|         189 | Jennifer    | Dilly       | JDILLY   | 650.505.2876       | 1987-09-14 | SH_CLERK   |  3600.00 |           0.00 |        122 |            50 |
|         190 | Timothy     | Gates       | TGATES   | 650.505.3876       | 1987-09-15 | SH_CLERK   |  2900.00 |           0.00 |        122 |            50 |
|         191 | Randall     | Perkins     | RPERKINS | 650.505.4876       | 1987-09-16 | SH_CLERK   |  2500.00 |           0.00 |        122 |            50 |
|         192 | Sarah       | Bell        | SBELL    | 650.501.1876       | 1987-09-17 | SH_CLERK   |  4000.00 |           0.00 |        123 |            50 |
|         193 | Britney     | Everett     | BEVERETT | 650.501.2876       | 1987-09-18 | SH_CLERK   |  3900.00 |           0.00 |        123 |            50 |
|         194 | Samuel      | McCain      | SMCCAIN  | 650.501.3876       | 1987-09-19 | SH_CLERK   |  3200.00 |           0.00 |        123 |            50 |
|         195 | Vance       | Jones       | VJONES   | 650.501.4876       | 1987-09-20 | SH_CLERK   |  2800.00 |           0.00 |        123 |            50 |
|         196 | Alana       | Walsh       | AWALSH   | 650.507.9811       | 1987-09-21 | SH_CLERK   |  3100.00 |           0.00 |        124 |            50 |
|         197 | Kevin       | Feeney      | KFEENEY  | 650.507.9822       | 1987-09-22 | SH_CLERK   |  3000.00 |           0.00 |        124 |            50 |
|         198 | Donald      | OConnell    | DOCONNEL | 650.507.9833       | 1987-09-23 | SH_CLERK   |  2600.00 |           0.00 |        124 |            50 |
|         199 | Douglas     | Grant       | DGRANT   | 650.507.9844       | 1987-09-24 | SH_CLERK   |  2600.00 |           0.00 |        124 |            50 |
|         200 | Jennifer    | Whalen      | JWHALEN  | 515.123.4444       | 1987-09-25 | AD_ASST    |  4400.00 |           0.00 |        101 |            10 |
|         201 | Michael     | Hartstein   | MHARTSTE | 515.123.5555       | 1987-09-26 | MK_MAN     | 13000.00 |           0.00 |        100 |            20 |
|         202 | Pat         | Fay         | PFAY     | 603.123.6666       | 1987-09-27 | MK_REP     |  6000.00 |           0.00 |        201 |            20 |
|         203 | Susan       | Mavris      | SMAVRIS  | 515.123.7777       | 1987-09-28 | HR_REP     |  6500.00 |           0.00 |        101 |            40 |
|         204 | Hermann     | Baer        | HBAER    | 515.123.8888       | 1987-09-29 | PR_REP     | 10000.00 |           0.00 |        101 |            70 |
|         205 | Shelley     | Higgins     | SHIGGINS | 515.123.8080       | 1987-09-30 | AC_MGR     | 12000.00 |           0.00 |        101 |           110 |
|         206 | William     | Gietz       | WGIETZ   | 515.123.8181       | 1987-10-01 | AC_ACCOUNT |  8300.00 |           0.00 |        205 |           110 |
+-------------+-------------+-------------+----------+--------------------+------------+------------+----------+----------------+------------+---------------+

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 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 Te  10934        Venice                      IT
1200         2017 Shinjuku-ku      1689         Tokyo       Tokyo Prefectu  JP
1300         9450 Kamiya-cho       6823         Hiroshima                   JP
1400         2014 Jabberwocky Rd   26192        Southlake   Texas           US
1500         2011 Interiors Blvd   99236        South San   California      US
1600         2007 Zagora St        50090        South Brun  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 Stree  2901         Sydney      New South Wale  AU
2300         198 Clementi North    540198       Singapore                   SG
2400         8204 Arthur St                     London                      UK
2500         Magdalen Centre, The  OX9 9ZB      Oxford      Oxford          UK
2600         9702 Chester Road     9629850293   Stretford   Manchester      UK
2700         Schwanthalerstr. 703  80925        Munich      Bavaria         DE
2800         Rua Frei Caneca 1360  01307-002    Sao Paulo   Sao Paulo       BR
2900         20 Rue des Corps-Sai  1730         Geneva      Geneve          CH
3000         Murtenstrasse 921     3095         Bern        BE              CH
3100         Pieter Breughelstraa  3029SK       Utrecht     Utrecht         NL
3200         Mariano Escobedo 999  11932        Mexico Cit  Distrito Feder  MX

SQLite Code:

-- Selecting the first name and last name of employees
SELECT first_name, last_name FROM employees 
-- Filtering the results to include only rows where the manager_id is in a subquery result
WHERE manager_id in (
  -- Subquery to retrieve the employee_id values
  select employee_id 
  -- Specifying the table from which to retrieve the data, in this case, "employees"
  FROM employees 
  -- Filtering the results to include only rows where the department_id is in another subquery result
  WHERE department_id 
    IN (
      -- Subquery to retrieve the department_id values
      SELECT department_id FROM departments 
      -- Filtering the results to include only rows where the location_id is in yet another subquery result
      WHERE location_id 
        IN (
          -- Subquery to retrieve the location_id values
          select location_id from locations 
          -- Filtering the results to include only rows where the country_id is 'US'
          where country_id='US'
        )
    )
);

Output:

first_name  last_name
----------  ----------
Neena       Kochhar
Lex         De Haan
Alexander   Hunold
Bruce       Ernst
David       Austin
...			...
Michael     Hartstein
Susan       Mavris
Hermann     Baer
Shelley     Higgins
William     Gietz

Explanation:

The above SQLite query selects the first name and last name of employees from the "employees" table. It includes only those employees whose 'manager_id' is in a hierarchy of subqueries, involving the "employees," "departments," and "locations" tables. The subqueries filter employees based on their department's location and the country of that location.

Here's a brief explanation of each part of SQLite code:

  • SELECT clause:
    • It selects the "first_name" and "last_name" columns.
  • FROM clause:
    • Specifies the table from which to retrieve the data, in this case, the "employees" table.
  • WHERE clause:
    • Filters the results to include only rows where the "manager_id" is in a subquery result.
  • Subquery 1:
    • The first subquery (select employee_id FROM employees WHERE department_id IN ...) retrieves the "employee_id" values.
    • It filters employees based on the "department_id" values obtained from the second subquery.
  • Subquery 2:
    • The second subquery (SELECT department_id FROM departments WHERE location_id IN ...) retrieves the "department_id" values.
    • It filters departments based on the "location_id" values obtained from the third subquery.
  • Subquery 3:
    • The third subquery (select location_id from locations where country_id='US') retrieves the "location_id" values.
    • It filters locations based on the "country_id" values being 'US'.

Practice SQLite Online


Model Database

Employee Model  Database - w3resource online SQLite practice

Structure of 'hr' database :

hr database

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Previous: Write a query to find the names (first_name, last_name) of all employees who works in the IT department.
Next: Write a query to find the names (first_name, last_name) of the employees who are managers.

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