Common methods for SQL Server

Calculating string Lengths
Len () is used to calculate the length of a string

Select sname,len from student

Convert string to large, lowercase
Lower () is used to convert a string to lowercase, and upper () is used to convert a string to uppercase

Select Lower ('I AM A STUDENT! ' )SelectUpper('I am a student! ')

to truncate the left and right spaces of a string
LTrim () is used to remove a space to the left of a string, and RTrim () is used to remove the space to the right of a string

Declare @str varchar( -)Set @str='There are spaces on my left! 'Select @str  asInitial character,Len(@str) asInitial length,LTrim(@str) asExisting characters,Len(LTrim(@str)) asExisting length

substring
substring (string,start_position,length) can take substrings of any length from any location,
Left (string,length)   Take substring
Right (string,length) from the left to the substring

 select  substring  ( '   

String substitution
Replace (string, strings to be replaced, strings replaced)

Select Replace ('helloworld! ','o','e') Result: hellewerld!

Returns the inverse value of a string value
Reverse (string_expression)

Select Reverse ('abc') Result: CBA

Deletes a specified length of character and inserts another set of characters at the specified starting point
Stuff (character_expression, start, length, character_expression)
Start an integer value that specifies the start position of the delete and insert.
Length An integer that specifies the number of characters to delete.

Select Stuff ('abcdefg',1,6,') Result: Hello g

Repeats a string value at a specified number of times
Replicate (String_Expression, integer_expression)

Select Replicate ('abc',4)  

Returns the starting position of the specified expression in the string
CHARINDEX (expression1, expression2, start_location) or charindex (expression1, expression2)
expression1 start position in expression2

Select charindex ('H','ellohworld')  The result is:5

Returns the starting position of the first occurrence of the pattern in the specified expression
Patindex ('%pattern% ', expression) returns the starting position of the first occurrence of a pattern in a specified expression;
If the pattern is not found in all valid text and character data types, zero is returned.

Select Patindex ('%hello%','worldhello') The result is:6

Returns an integer value of the first character of an input expression
Unicode (' ncharacter_expression ') ' ncharacter_expression ' expression for nchar or nvarchar Expression

Select Unicode ('a')  The result isas follows: The result of the ". *Unicode('abc') is:

Common methods for SQL Server