A scalar function in SQL is a type of function that operates on individual values, returning a single result for each input value. Unlike aggregate functions, which operate on sets of values and return a single result for the entire set, scalar functions work on each row independently. These functions can perform various operations such as string manipulation, mathematical calculations, date/time operations, and type conversion. Scalar functions are commonly used within SELECT statements, WHERE clauses, and expressions to transform or manipulate data on a row-by-row basis.
- String Functions:
- CONCAT: Concatenates two or more strings.
- SUBSTRING: Extracts a substring from a string.
- UPPER/UCASE: Converts a string to uppercase.
- LOWER/LCASE: Converts a string to lowercase.
- TRIM: Removes leading and trailing spaces from a string.
- LENGTH/LEN: Returns the length of a string.
- Numeric Functions:
- ABS: Returns the absolute value of a number.
- ROUND: Rounds a number to a specified number of decimal places.
- CEILING: Rounds a number up to the nearest integer.
- FLOOR: Rounds a number down to the nearest integer.
- SQRT: Returns the square root of a number.
- Date and Time Functions:
- DATEADD: Adds a specified time interval to a date.
- DATEDIFF: Calculates the difference between two dates.
- DATEPART: Returns a specific part of a date (e.g., year, month, day).
- GETDATE/NOW: Returns the current date and time.
- DATE_FORMAT: Formats a date according to a specified format.
- Conversion Functions:
- CAST/CONVERT: Converts a value from one data type to another.
- COALESCE: Returns the first non-null value in a list of expressions.
- Mathematical Functions:
- SIN, COS, TAN: Trigonometric functions.
- LOG, LOG10, EXP: Logarithmic functions.
These functions can be used in SQL queries to perform various operations on data, depending on the specific requirements of the task at hand.
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