[functions] more functions working with string

[junnplus]

Summary

https://dev.mysql.com/doc/refman/8.0/en/string-functions.html

Tasks list:

If you are interested in one or more tasks in this issue, you can comment like: /assignme in the subtask issue to make this subtask assigned to you.

• ASCII() | Return numeric value of left-most character #3014
• BIN() | Return a string containing binary representation of a number #3015
• BIT_LENGTH() | Return length of argument in bits #3016
• CHAR() | Return the character for each integer passed #3017
• CHAR_LENGTH() | Return number of characters in argument #3018
• CHARACTER_LENGTH() | Synonym for CHAR_LENGTH() #3019
• CONCAT() | Return concatenated string #3020
• CONCAT_WS() | Return concatenate with separator #3021
• ELT() | Return string at index number #3022
• EXPORT_SET() | Return a string such that for every bit set in the value bits, you get an on string and for every unset bit, you get an off string #3023
• FIELD() | Index (position) of first argument in subsequent arguments #3024
• FIND_IN_SET() | Index (position) of first argument within second argument #3025
• FORMAT() | Return a number formatted to specified number of decimal places #3028
• FROM_BASE64() | Decode base64 encoded string and return result #3034
• HEX() | Hexadecimal representation of decimal or string value #3041
• INSERT() | Insert substring at specified position up to specified number of characters #3043
• INSTR() | Return the index of the first occurrence of substring #3044
• LCASE() | Synonym for LOWER() #3011
• LEFT() | Return the leftmost number of characters as specified #3046
• LENGTH() | Return the length of a string in bytes #3049
• LIKE | Simple pattern matching #3051
• LOAD_FILE() | Load the named file #3059
• LOCATE() | Return the position of the first occurrence of substring #3060
• LOWER() | Return the argument in lowercase #3010
• LPAD() | Return the string argument, left-padded with the specified string #3058
• LTRIM() | Remove leading spaces #3061
• MID() | Return a substring starting from the specified position #3064
• NOT LIKE | Negation of simple pattern matching #3066
• NOT REGEXP | Negation of REGEXP #3067
• OCT() | Return a string containing octal representation of a number #3074
• OCTET_LENGTH() | Synonym for LENGTH() #3070
• ORD() | Return character code for leftmost character of the argument #3072
• POSITION() | Synonym for LOCATE() #3075
• QUOTE() | Escape the argument for use in an SQL statement #3073
• REGEXP | Whether string matches regular expression #3071
• REGEXP_INSTR() | Starting index of substring matching regular expression #3069
• REGEXP_LIKE() | Whether string matches regular expression #3065
• REGEXP_SUBSTR() | Return substring matching regular expression #3056
• REPEAT() | Repeat a string the specified number of times #3055
• REPLACE() | Replace occurrences of a specified string #3054
• REVERSE() | Reverse the characters in a string #3053
• RIGHT() | Return the specified rightmost number of characters #3052
• RLIKE | Whether string matches regular expression #3050
• RPAD() | Append string the specified number of times #3048
• RTRIM() | Remove trailing spaces #3047
• SOUNDEX() | Return a soundex string #3045
• SPACE() | Return a string of the specified number of spaces #3040
• STRCMP() | Compare two strings #3039
• SUBSTR() | Return the substring as specified #3037
• SUBSTRING() | Return the substring as specified #3035
• SUBSTRING_INDEX() | Return a substring from a string before the specified number of occurrences of the delimiter #3033
• TO_BASE64() | Return the argument converted to a base-64 string #3032
• TRIM() | Remove leading and trailing spaces #3030
• UCASE() | Synonym for UPPER() #3012
• UNHEX() | Return a string containing hex representation of a number #3031
• UPPER() | Convert to uppercase #3013

Lower Priority:

• MAKE_SET() | Return a set of comma-separated strings that have the corresponding bit in bits set #3062
• MATCH() | Perform full-text search #3063
• SOUNDS LIKE | Compare sounds #3042
• WEIGHT_STRING() | Return the weight string for a string #3026
• REGEXP_REPLACE() | Replace substrings matching regular expression #3057

Ref:
more functions working with number
How to write scalar functions

[junnplus]

@sundy-li Help add a good first issue label.

[Xuanwo]

/assignme LOWER LCASE UPPER UCASE

They are similar functions, so I think it's OK to take them at the same time.

[zhang2014]

/assignme LOWER LCASE UPPER UCASE
They are similar functions, so I think it's OK to take them at the same time.

I converted them as issues. CC: @Xuanwo

[mshauneu]

/assignme FROM_BASE64() TO_BASE64()

[radmirnovii]

/assignme BIT_LENGTH() LENGTH()

[Veeupup]

@sundy-li may pin #3967 on the board and make this unpin?

[sundy-li]

This task is almost done! The rest functions will be taken as low priority (We can add them anytime if users need them).

Thanks for the contributions !!!