SQL wildcards are like placeholders that help you find patterns in your data when you’re working with a database. They are super handy when you want to search for something, but you are not entirely sure about the exact value you are looking for. They are mostly used with the LIKE operator in SQL queries.
For example:
• The % wildcard represents zero, one, or multiple characters. So, if you search for something like ‘Ke%’, it will match anything starting with “Ke,” like “Kenneth” or “Kennedy.”
• The _ wildcard matches exactly one character. If you use ‘J_n’, it will match “Jon” or “Jan,” but not “John.”
Think of them as shortcuts that make searching through your database more flexible and efficient. If you’ve got a massive table of names or products, SQL wildcards can save you a ton of time by narrowing down results even when details are fuzzy. Pretty neat, right?
SQL Character Range Wildcard Usage Explained
Syntax:
Explanation:
• [ ] is used to specify a range or set of characters.
• You can define a range of characters using a hyphen – inside the brackets.
• The LIKE operator is used to search for a specified pattern in a column.
Examples:
- Match any single character within a range:
o To find names that start with any letter from ‘A’ to ‘D’.
Syntax:
• [A-D] matches any single character from ‘A’ to ‘D’.
• % matches any sequence of characters after the first character.
- Match any single character from a specific set:
o To find names that start with ‘A’, ‘B’, or ‘C’.
Syntax:
• [ABC] matches any single character that is ‘A’, ‘B’, or ‘C’.
- Match any single character outside a range:
o To find names that do not start with any letter from ‘A’ to ‘D’.
Syntax:
• [^A-D] matches any single character that is not in the range ‘A’ to ‘D’.
- Match a combination of ranges and specific characters:
o To find names that start with ‘A’ to ‘D’ or ‘X’ to ‘Z’.
Syntax:
• [A-DX-Z] matches any single character from ‘A’ to ‘D’ or ‘X’ to ‘Z’.
Notes:
• The [] wildcard is supported in SQL Server and some other databases like PostgreSQL.
• In MySQL, the [] wildcard is not supported. Instead, you can use regular expressions with the REGEXP operator for similar functionality.
For example, in MySQL:
Syntax:
• ^[A-D] matches any name that starts with a character from ‘A’ to ‘D’.
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