Sql 简明教程

SQL - String Functions

SQL 字符串函数主要用于字符串处理。下表列出了重要的字符串函数：

SQL string functions are used primarily for string manipulation. The following table details the important string functions −

Sr.No.	Function & Description
1	ASCII()Returns numeric value of left-most character
2	CHAR()Returns the character for each integer passed
3	CHARINDEX()Returns the position of a substring within the given string.
4	CONCAT_WS()Returns concatenate with separator
5	CONCAT()Returns concatenated string
6	DIFFERENCE()returns an integer value measuring the difference between the SOUNDEX() values of two different expressions(strings).
7	ESCAPE()Returns a text with escaped characters.
8	FORMAT()Returns the formatted string.
9	LEFT()Returns the extracting string.
10	LEN()Returns the length of the given string.
11	LOWER()Returns returns the lower case of the given string.
12	LTRIM()Returns a string after removing all the white spaces and characters from the string found on the left side.
13	NCHAR()Returns the Unicode character based on the number code.
14	PATINDEX()Returns the position of a pattern in a string.
15	QUOTENAME()Returns a string with a delimiter
16	REPLACE()Returns a new string by replacing all the occurrences of the particular part of a string (substring) with a specified string.
17	REPLICATE()Returns the repeated value.
18	REVERSE()Returns a reversed string.
19	RIGHT()Returns the rightmost characters from the actual(current) string.
20	RTRIM()Returns a string after removing all trailing blanks.
21	SOUNDEX()Returns the Soundex string.
22	SPACE()returns a string consisting of N number of space characters.
23	STR()Returns a number as string.
24	STRING_AGG()Concatenates the values of string expressions and places separator values between them.
25	STRING_SPLIT()Splits a string into rows of substrings.
26	STUFF()Returns a new string by inserting the second expression at the specified deleted place.
27	SUBSTRING()Returns the part of the character.
28	TRANSLATE()Returns a string from the first argument.
29	TRIM()Returns a trimmed string.
30	UNICODE()Returns an integer value of the first character.
31	UPPER()returns a string that has all the characters in upper case.