SQL String Functions

CONCAT Function

The CONCAT function combines multiple strings into a single string. It is useful when you want to merge columns or add text to existing data.

• Syntax: CONCAT(string1, string2, ...)
• Returns a single concatenated string.

SUBSTRING Function

SUBSTRING extracts a part of a string starting at a specified position for a given length. This is helpful for parsing or trimming data.

• Syntax: SUBSTRING(string, start_position, length)
• Positions start at 1 in most SQL dialects.

LENGTH Function

LENGTH returns the number of characters in a string, including spaces. It helps in validating or filtering data based on string size.

• Syntax: LENGTH(string)
• Returns an integer representing string length.

UPPER and LOWER Functions

These functions convert all characters in a string to uppercase or lowercase, respectively. Useful for case-insensitive comparisons or formatting.

• Syntax: UPPER(string) or LOWER(string)
• Returns the string in the specified case.

TRIM Function

TRIM removes unwanted spaces from the beginning and end of a string, which is common when cleaning data.

• Syntax: TRIM(string)
• Returns the string without leading or trailing spaces.

Concatenating First and Last Names

Combine first and last name columns into a full name.

Extracting Area Code from Phone Number

Use SUBSTRING to get the area code from a phone number string.