SQL [charlist] wildcards

[charlist] wildcards

The [charlist] WILDCARDS are used to represent any single character within a charlist.

The [^charlist] and [!charlist] WILDCARDS is used to represents any single character not in the charlist.

Example:

+------------+----------------------+--------------------+------------+-----------------+---------+
| AGENT_CODE | AGENT_NAME           | WORKING_AREA       | COMMISSION | PHONE_NO        | COUNTRY |
+------------+----------------------+--------------------+------------+-----------------+---------+
| A007       | Ramasundar           | Bangalore          |       0.15 | 077-25814763    |         |
| A003       | Alex                 | London             |       0.13 | 075-12458969    |         |
| A008       | Alford               | New York           |       0.12 | 044-25874365    |         |
| A011       | Ravi Kumar           | Bangalore          |       0.15 | 077-45625874    |         |
| A010       | Santakumar           | Chennai            |       0.14 | 007-22388644    |         |
| A012       | Lucida               | San Jose           |       0.12 | 044-52981425    |         |
| A005       | Anderson             | Brisban            |       0.13 | 045-21447739    |         |
| A001       | Subbarao             | Bangalore          |       0.14 | 077-12346674    |         |
| A002       | Mukesh               | Mumbai             |       0.11 | 029-12358964    |         |
| A006       | McDen                | London             |       0.15 | 078-22255588    |         |
| A004       | Ivan                 | Torento            |       0.15 | 008-22544166    |         |
| A009       | Benjamin             | Hampshair          |       0.11 | 008-22536178    |         |
+------------+----------------------+--------------------+------------+-----------------+---------+

To get all rows from the table 'agents' with following condition -

1. the 'agent_name' must begin with the letter 'a' or 'b' or 'i'

the following sql statement can be used :

SELECT *
-- Select all columns
FROM agents
-- From the table named "agents"
WHERE agent_name  LIKE '[abi]%';
-- Where the agent_name starts with 'a', 'b', or 'i', followed by any characters

Explanation:

• SELECT *: This statement selects all columns from the specified table.


• FROM agents: This specifies the table from which to retrieve data, in this case, the table named "agents".


• WHERE agent_name LIKE '[abi]%': This is the conditional clause that filters the rows returned by the query. It uses the LIKE operator to match patterns in the agent_name column. So, it looks for rows where the agent_name starts with the characters '['a', 'b', or 'i']' followed by any characters due to the '%' wildcard.

Relational Algebra Expression:

Relational Algebra Tree:

Sql [^charlist] wildcards

+------------+----------------------+--------------------+------------+-----------------+---------+
| AGENT_CODE | AGENT_NAME           | WORKING_AREA       | COMMISSION | PHONE_NO        | COUNTRY |
+------------+----------------------+--------------------+------------+-----------------+---------+
| A007       | Ramasundar           | Bangalore          |       0.15 | 077-25814763    |         |
| A003       | Alex                 | London             |       0.13 | 075-12458969    |         |
| A008       | Alford               | New York           |       0.12 | 044-25874365    |         |
| A011       | Ravi Kumar           | Bangalore          |       0.15 | 077-45625874    |         |
| A010       | Santakumar           | Chennai            |       0.14 | 007-22388644    |         |
| A012       | Lucida               | San Jose           |       0.12 | 044-52981425    |         |
| A005       | Anderson             | Brisban            |       0.13 | 045-21447739    |         |
| A001       | Subbarao             | Bangalore          |       0.14 | 077-12346674    |         |
| A002       | Mukesh               | Mumbai             |       0.11 | 029-12358964    |         |
| A006       | McDen                | London             |       0.15 | 078-22255588    |         |
| A004       | Ivan                 | Torento            |       0.15 | 008-22544166    |         |
| A009       | Benjamin             | Hampshair          |       0.11 | 008-22536178    |         |
+------------+----------------------+--------------------+------------+-----------------+---------+

To get all rows from the table 'agents' with following condition -

1.the 'agent_name' must not begin with the letter 'a' or 'b' or 'i',

the following sql statement can be used :

SELECT *
-- Select all columns
FROM agents
-- From the table named "agents"
WHERE agent_name  LIKE '[^abi]%';
-- Where the agent_name doesn't start with 'a', 'b', or 'i', followed by any characters

Explanation:

• SELECT *: This statement selects all columns from the specified table.


• FROM agents: This specifies the table from which to retrieve data, in this case, the table named "agents".


• WHERE agent_name LIKE '[^abi]%': This is the conditional clause that filters the rows returned by the query. It uses the LIKE operator to match patterns in the agent_name column.

Relational Algebra Expression:

Relational Algebra Tree:

Sql [!charlist] wildcards

+------------+----------------------+--------------------+------------+-----------------+---------+
| AGENT_CODE | AGENT_NAME           | WORKING_AREA       | COMMISSION | PHONE_NO        | COUNTRY |
+------------+----------------------+--------------------+------------+-----------------+---------+
| A007       | Ramasundar           | Bangalore          |       0.15 | 077-25814763    |         |
| A003       | Alex                 | London             |       0.13 | 075-12458969    |         |
| A008       | Alford               | New York           |       0.12 | 044-25874365    |         |
| A011       | Ravi Kumar           | Bangalore          |       0.15 | 077-45625874    |         |
| A010       | Santakumar           | Chennai            |       0.14 | 007-22388644    |         |
| A012       | Lucida               | San Jose           |       0.12 | 044-52981425    |         |
| A005       | Anderson             | Brisban            |       0.13 | 045-21447739    |         |
| A001       | Subbarao             | Bangalore          |       0.14 | 077-12346674    |         |
| A002       | Mukesh               | Mumbai             |       0.11 | 029-12358964    |         |
| A006       | McDen                | London             |       0.15 | 078-22255588    |         |
| A004       | Ivan                 | Torento            |       0.15 | 008-22544166    |         |
| A009       | Benjamin             | Hampshair          |       0.11 | 008-22536178    |         |
+------------+----------------------+--------------------+------------+-----------------+---------+

To get all rows from the table 'agents' with following condition -

1.the 'agent_name' must not begin with the letter 'a' or 'b' or 'i',

the following sql statement can be used :

SELECT *
-- Select all columns
FROM agents 
-- From the table named "agents"
WHERE agent_name  LIKE '[!abi]%';
-- Where the agent_name starts with any character except 'a', 'b', or 'i', followed by any characters

Explanation:

• SELECT *: This statement selects all columns from the specified table.


• FROM agents: This specifies the table from which to retrieve data, in this case, the table named "agents".


• WHERE agent_name LIKE '[!abi]%': This is the conditional clause that filters the rows returned by the query. It uses the LIKE operator to match patterns in the agent_name column.

Relational Algebra Expression:

Relational Algebra Tree:

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