If you want to be an expert in sql server, then you should learn SQL Server functions. Here, we will guide you and teach you everything about functions in sql server with examples.
What is a Function in SQL Server?
In SQL Server, a function is a pre-written code segment that performs a specific task and returns a value. It’s essentially a set of SQL statements that you can call by name to perform an operation, often with input parameters and returning a result. Functions in SQL Server are broadly classified into two categories:
Types of SQL Server Functions
Built-In Functions
SQL Server provides a vast library of built-in functions. These functions are pre-defined and can be utilized without the need for user-defined code. They are broadly classified into categories such as string functions, mathematical functions, date and time functions, and more. Some key built-in functions include:
- String Functions: Functions like LEN, SUBSTRING, and REPLACE are used for string manipulation.
- Mathematical Functions: Functions such as ROUND, FLOOR, and CEILING assist in mathematical calculations.
- Date and Time Functions: Functions like GETDATE, DATEADD, and DATEDIFF are essential for handling date and time data.
User-Defined Functions
These are functions created by users to meet specific requirements not covered by built-in functions. UDFs can return either a single scalar value or a result set. UDFs can be written in Transact-SQL or CLR languages (like C# or VB.NET). They are especially useful for encapsulating complex logic that can be reused across multiple queries. UDFs can be further classified into:
- Scalar Functions: These return a single value based on the input value.
- Table-Valued Functions: These return a table and can be used like a regular table in SQL queries.
Advantages of Using SQL Server Functions
- Efficiency: Functions reduce the amount of code required, making database queries more efficient.
- Reusability: Functions, especially UDFs, can be reused across multiple SQL queries, saving time and effort.
- Modularity: Breaking down complex logic into functions enhances the readability and maintainability of code.
- Performance: Certain functions can optimize query performance by simplifying complex operations.
SQL Server string functions with examples
Here, check out all the sql server string functions with examples.
| Functions | Descriptions |
|---|---|
| CAST Function in SQL Server | Learn how to convert the datatype of the value to another datatype using the cast() function in the sql server. |
| CONVERT Function in SQL Server | This sql server tutorial explains how to alter the datatype of the value to a different datatype using the convert() function. |
| LEFT Function in SQL Server | Learn how to extract the leftmost characters from the string using the LEFT() function in the sql server. |
| RIGHT Function in SQL Server | This sql server tutorial explains how to extract the rightmost characters from the string using the RIGHT() function in sql server. |
| LEN Function in SQL Server | This sql server tutorial explains how to find the length of the string using the LEN() function in sql server. |
| Format Function in SQL SERVER | Learn how to format the provided value based on the different format patterns in the sql server using the format() function. |
| CHAR Function in SQL Server | This sql server tutorial explains how to get the characters based on the provided integer value using the CHAR() function in sql server. |
| SQL Server RTRIM Function | Learn how to remove the trailing spaces or the other specified characters from the string using the RTRIM() function in the sql server. |
| SQL Server LTRIM Function | Learn how to remove the leading spaces or the other specified characters from the string using the LTRIM() function in the sql server. |
| SQL Server STR Function | This sql server tutorial explains how to convert the given float number to a character value using the STR() function in sql server. |
| REPLACE Function in SQL Server | This sql server tutorial explains how to substitute a new string in place of the sub-part of the given string using the REPLACE() function in sql server. |
| UPPER Function in SQL Server | Learn how to transform the given string value to uppercase using the UPPER() function in the sql server. |
| LOWER Function in SQL Server | Learn how to transform the given string value to lowercase using the LOWER() function in the sql server. |
| REPLICATE Function of SQL Server | This sql server tutorial explains how to replicate the given character or string a specified number of times using the REPLICATE() function in sql server. |
| TRY_CONVERT Function in SQL Server | Learn how to convert the value’s data type to another data type using the TRY_CONVERT() function that has error-handling capabilities. |
| SQL Server STRING_AGG Function | Learn how to concatenate multiple string values into single string values, and those concatenated strings are separated with a separator using the STRING_AGG() function in the sql server. |
| STRING_SPLIT Function in SQL Server | This tutorial explains how to split the specified string into substrings based on the specified delimiter or separator using the STRING_SPLIT() function in the sql server. |
| STRING_ESCAPE Function in SQL Server | Do you know how to escape the special character in the string in your query? if not, use the STRING_ESCAPE() function of the sql server to escape the special characters in the string. |
| DATALENGTH Function in SQL Server | This sql server tutorial explains how to find the length of the string in bytes using the DATALENGTH() function. |
| CHARINDEX Function in SQL Server | Learn how to find the starting position of a substring in the given string using the CHARINDEX() function in the sql server. |
| SUBSTRING Function in SQL Server | If you have a situation where you need to extract a certain length of a substring from the specific position in the string, use the SUBSTRING() function in the sql server. |
| SQL Server REVERSE() | Learn how to reverse the characters of the given string using the REVERSE() function in the sql server. |
| DIFFERENCE Function in SQL Server | This sql server tutorial explains how to find the similarity between strings based on their sound using the DIFFERENCE() function in the sql server. |
| SPACE Function in SQL Server | Learn how to generate a certain number of space characters using the SPACE() function in the sql server. |
| TRIM Function in SQL Server | This tutorial explains how to remove the spaces or any characters from the beginning and end of the string using the TRIM() function in the sql server. |
| TRANSLATE Function in SQL Server | If you want to know how to substitute new characters in place of existing characters in a string, use the TRANSLATE() function in the sql server. |
| QUOTENAME function in SQL Server | Learn how to add the delimiters around the string and return the string with the delimiter around it using QUOTENAME() function in the sql server. |
| SQL Server UNICODE Function | If you want to know the integer value of the beginning character of the given input expression corresponding to the specific characters in the UNICODE standard, use UNICODE() function in the sql server. |
| PATINDEX Function in SQL Server | This tutorial explains how to find the starting index of the substring or pattern in the source string using the PATINDEX() function in the sql server. |
| ISNULL Function in SQL Server | Learn how to replace the null value in a table column with a new value using the ISNULL() function in the sql server. |
| ISJSON Function in SQL Server | Learn how to check whether a string contains the JSON value using the ISJSON() function in the sql server. |
SQL Server date functions with examples
This section explains how to work with date functions in sql server with examples.
| Functions | Descriptions |
|---|---|
| How to Use CURRENT_TIMESTAMP Function in SQL Server | Learn how to get the current date and time of the system using the CURRENT_TIMESTAMP function in sql server. |
| How to use GETDATE Function in SQL Server | This sql server tutorial explains how to return the current datetime value of the system using the GETDATE() function in sql server. |
| SYSDATETIMEOFFSET Function in SQL Server | Learn how to get the system date and time with timezone offset using the SYSDATETIMEOFFSET() function in sql server. |
| How to use SYSDATETIME Function in SQL Server | This sql server tutorial explains how to retrieve the system’s current date and time with high precision using the SYSDATETIME() function in sql server. |
| SYSUTCDATETIME Function in SQL Server | Learn how to return the system date and time in UTC format using the SYSUTCDATETIME() function in the sql server. |
| DATENAME Function of SQL Server | This sql server tutorial explains how to get the specific part of the date, such as year, month, etc using the DATENAME() function in sql server. |
| DATEPART Function in SQL Server | Learn how to extract the specific part ( such as year, month, day, hour, etc) of the date using the DATEPART() function in SQL Server. |
| SQL Server DATETRUNC Function | This sql server tutorial explains how to truncate the specific part of the given date using the DATETRUNCC function in the sql server. |
| DAY Function in SQL Server | Learn how to extract the day part from the given date using the DAY() function in the sql server. |
| How to use SQL Server DATE_BUCKET Function | This sql server tutorial explains how to create a data bucket based on the datatime value using the DATE_BUCKET() function in the sql server. |
| MONTH Function in SQL Server | If you want to learn how to extract the month part from the specified date, use the MONTH() function of the sql server. |
| YEAR Function in SQL Server | This sql server tutorial explains the YEAR() function to extract the year part of the date value. |
| DATEDIFF Function in SQL Server | If you have two dates and want to find the difference between two dates in month, day, etc., try the DATEDIFF() function in the sql server. |
| ISDATE Function in SQL Server | This tutorial explains how to check if the given expression contains a valid date value or not using the ISDATE() function in the sql server. |
| DATEADD Function in SQL Server | Learn how to add the date components, such as month, year, etc, to the existing date using the DATEADD() function in the sql server. |
| SQL DATEFROMPARTS Function | If you have date parts and want to create a completed date from the date parts, use the DATEFROMPARTS() function in the sql server. |
| TIMEFROMPARTS Function in SQL Server | If you have time parts and want to create a completed time from the time parts, use the TIMEROMPARTS() function in the sql server. |
| How to use SQL Server EOMONTH Function | Learn how to find the last day of the month of the specified data using the EOMONTH() function in the sql server. |
Aggregate functions in SQL Server with examples
Check out all the tutorials on aggregate functions in SQL Server with examples:
| Functions | Descriptions |
|---|---|
| How to use COUNT Function in SQL Server | This sql server tutorial explains the COUNT() aggregate function to count the number of rows in a table. |
| How to use SUM Function in SQL Server | Learn how to compute the sum of all the values in a table column using the SUM() function in sql server. |
| How to use AVG Function in SQL Server | This sql server tutorial explains how to compute the average value of a set of values ( of table column) using the AVG() function in sql server. |
| How to use MAX Function in SQL Server | Learn how to find the maximum value from the table column using the MAX() function in the sql server. |
| How to use MIN Function in SQL Server | Learn how to find the minimum value from the table column using the MIN() function in the sql server. |
| GROUPING in SQL Server | This tutorial explains the GROUPING() function in SQL Server that determines whether a row is an aggregated result of GROUP BY operation. |
| How to use VAR Function in SQL Server | Learn how to compute the variance of the sample data using the VAR() function in the sql server. |
| STDEV Function in SQL Server | Learn how to calculate the standard deviation of the sample data using the STDEV() function in the sql server. |
| How to use STDEVP Function in SQL Server | This tutorial explains how to find the standard deviation of the population data using the STDEVP() function in the sql server. |
| How to use VARP Function in SQL Server | Learn how to compute the variance of the population data using the VAR() function in the sql server. |
| CHECKSUM_AGG Function in SQL Server | Sometimes, you need to detect the changes on a table or want to know whether the value of a column changed; in that case, use the CHECKSUM_AGG() function in the SQL server to detect the changes that occur to the table. |
| GROUPING_ID Function in SQL Server | To identify the grouping level in a query that uses ROLLUP or CUBE with a GROUP BY clause, use the GROUPING_ID() function in the sql server. |
| COUNT_BIG Function in SQL Server | If you want to count the number of rows in a table, you should know about COUNT_BIG() function in the sql server. |
Conclusion
I hope these SQL server function tutorials have helped you to become an expert in SQL Server. Functions are very important in SQL Server.