SQL-TSQL Functions

T-SQL functions

SQL Server built-in functions can be deterministic or indeterminate. If you call built-in functions at any time with a specific set of input values, the returned results are always the same, and these built-in functions are deterministic. If a built-in function is called each time it is used with the same set of specific input values and always returns different results, these built-in functions are indeterminate

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1) , character Conversion number of functions

2 ), go to space function

L LTRIM () the string Head the space is removed from the section.

Select LTRIM (' big ')

3 ), take the SUBSTRING function

L Left ()

Left (<character_expression>, <integer_expression>)

return character_expression from left integer_expression a character.

Select Left (' small_big ',4)

4 ), string ratio more function

L CHARINDEX ()

returns a specified substring in a string . now the starting position.

5 ), string manipulation functions

L QUOTENAME ()

Returns a string that is enclosed by a specific character.

6 ), Date function

pair date and time loss Enter value to hold row operation, then returns a string, number, or day period and Time Value

7 ), based on to be The parameters of the function provide the lose into value row operation, and then returns the number value

Name of function language Method say Ming

ABS ( number - valued expression ) Absolute Value .

8 ), Conversion Class Data Functions

there are two functions (CAST ()/convert) can move data from one dataclasstypeConversioninto another type of dataclass type. his ourthe difference is thatCAST ()haveANSI SQL-92the compatibility, whileCONVERT ()the work more for Strong Large .

9 ), aggregate functions:

Aggregation Functionsbyoften withSELECTlanguagesentence ofGROUP byclauses are used together. All aggregation functions areto beDeterminesex function, which issay, just use aGroupSpecialfixedloseintoValue Adjustmentwith aggregate functions,thefunctionTotalis to return the samevalue. it can betheaGroup of PractitionersLineCountcount, and return as avalue.

Function Name parameter description

AVG ([all| DISTINCT] expression) the mean value of the specified field in a mathematical expression , or

count All Record , or sub- Don't count counted the field on value not the same Record .

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SQL-TSQL Functions