Problem
Sometimes there is a need to manipulate string values using T-SQL code. With other languages such as Visual Basic, C++, C#, VBScript, etc… there are a lot of commands at your finger tips to manipulate string values. With SQL Server you don’t have all the same options, but there are enough commands that if correctly used together can result in the same functionality you get with other programming languages.
Solution
The following is a list of SQL Server T-SQL commands that exist to allow you to manipulate text data either from stored procedures, triggers, functions or embedded SQL code.
| Command | Description |
|---|---|
| CHARINDEX( findTextData, textData, [startingPosition] ) | Returns the starting position of the specified expression in a character string. The starting position is optional. |
| LEFT( character_expression , integer_expression ) | Returns the left part of a character string with the specified number of characters. |
| LEN( textData ) | Returns integer value of the length of the string, excluding trailing blanks |
| LOWER ( character_expression ) | Returns a character expression after converting uppercase character data to lowercase |
| LTRIM( textData) | Removes leading blanks |
| PATINDEX( findTextData, textData ) | Returns integer value of the starting position of text found in the string |
| REPLACE( textData, findTextData, replaceWithTextData ) | Replaces occurrences of text found in the string with a new value |
| REPLICATE( character_expression , integer_expression ) | Repeats a character expression for a specified number of times. |
| REVERSE( character_expression ) | Returns the reverse of a character expression. |
| RTRIM( textData) | Removes trailing blanks |
| SPACE( numberOfSpaces ) | Repeats space value specified number of times |
| STUFF( textData, start , length , insertTextData ) | Deletes a specified length of characters and inserts another set of characters at a specified starting point |
| SUBSTRING( textData, startPosition, length ) | Returns portion of the string |
| UPPER( character_expression ) | Returns a character expression with lowercase character data converted to uppercase. |
Examples
The examples below are just simple SELECT statements using hard coded values. You can use these functions when querying your tables, so you can manipulate the string values as you query your data and return the modified result.
| Query | Value |
|---|---|
| SELECT CHARINDEX(‘SQL’, ‘Microsoft SQL Server – SQL Server’) | 11 (SQL is found in the 11 position) |
| SELECT CHARINDEX(‘SQL’, ‘Microsoft SQL Server – SQL Server’, 20) | 24 (SQL is found in the 24 position, since we started looking in position 20) |
| SELECT LEFT(‘Microsoft SQL Server – SQL Server’ , 20 ) | Microsoft SQL Server (left 20 characters of the string) |
| SELECT LEN(‘Microsoft SQL Server – SQL Server’) | 33 (total length of the string) |
| SELECT LOWER(‘Microsoft SQL Server – SQL Server’) | microsoft sql server – sql server (string in lower case) |
| SELECT LTRIM( ‘ Microsoft SQL Server – SQL Server ‘) | Microsoft SQL Server – SQL Server (trimmed string removing leading spaces) |
| SELECT PATINDEX( ‘%SQL%’, ‘Microsoft SQL Server – SQL Server’ ) | 11 (SQL is found in the 11 position) |
| SELECT REPLACE( ‘Microsoft SQL Server – SQL Server’, ‘Server’, ‘Server 2005’ ) | Microsoft SQL Server 2005 – SQL Server 2005 (string after we replace ‘Server’ with ‘Server 2005’) |
| SELECT REPLICATE( ‘x’ , 10 ) | xxxxxxxxxx (x replicated 10 times) |
| SELECT REVERSE( ‘Microsoft SQL Server’ ) | revreS LQS tfosorciM (string in reverse) |
| SELECT RTRIM( ‘ Microsoft SQL Server – SQL Server ‘) | Microsoft SQL Server – SQL Server (string after removing trailing spaces) |
| SELECT ‘Microsoft’ + SPACE(10) + ‘SQL Server’ | Microsoft SQL Server (string after inserting 10 spaces) |
| SELECT STUFF( ‘Microsoft SQL Server’, 11 , 3 , ‘2005’ ) | Microsoft 2005 Server (string after replacing positions 11, 12, 13 with ‘2005’) |
| SELECT SUBSTRING( ‘Microsoft SQL Server’, 1, 9 ) | Microsoft (substring of statement starting at position 1 for 9 characters) |
| SELECT UPPER(‘Microsoft SQL Server – SQL Server’) | MICROSOFT SQL SERVER – SQL SERVER (string in upper case) |
In addition to using the commands by themselves you can use multiple commands at the same time to provide more meaningful results.
| Query | Value |
|---|---|
| SELECT LEFT(‘Microsoft SQL Server’, CHARINDEX(‘ ‘, ‘Microsoft SQL Server – SQL Server’,13) – 1) | Microsoft SQL (find portion of string where a space is found but starting at position 13) |
| SELECT LEFT(‘Microsoft SQL Server’, CHARINDEX(‘ ‘, ‘Microsoft SQL Server – SQL Server’) – 1) | Microsoft (find portion of string where a space is found) |
| SELECT LTRIM(RTRIM(‘ Microsoft SQL Server – SQL Server ‘)) | Microsoft SQL Server – SQL Server (trim leading and trailing spaces) |
Next Steps
- Get familiar with these commands and how they can be used to manipulate text data
- Look for ways of using multiple commands together to reach the desired results
