Section describes the function
--substring (field names, n, m) dividing a field string block from the n m-bit characters behind the characters
select SUBSTRING (NAME, 1,3), NAME from Student where ID = 1
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--STUFF (str1, n, m, str2) a first sub-string deleted from the n m-bit bit string is inserted into the second
select STUFF (NAME, 2,1, ' qqqqq'), Name from Student where ID = 1 
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--left function left (field, N number) from the left N characters
select left (NAME, 4), NAME from Student where ID = 1
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--right function right (field, N number) of N characters starting from the right
select right (NAME, 4), NAME from Student where ID = 1
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--REPLICATE function Repeat to specify the number of times a character expression
select REPLICATE(NAME,3),NAME from Student where ID=1
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- ltrim rtrim function and delete the spaces left and right spaces TRIM to the middle in order to use the space 2017SQl
select LTRIM(NAME),RTRIM(NAME),TRIM(NAME),NAME from Student where ID=1
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To be continued!