Return a substring. This function extracts a portion of a string starting at a specific position for a given length.
The forms without a len argument return a substring from string str starting at position pos.
The forms with a len argument return a substring len characters long from string str, starting at position pos.
The forms that use FROM are standard SQL syntax.
It is also possible to use a negative value for pos. In this case, the beginning of the substring is pos characters from the end of the string, rather than the beginning. A negative value may be used for pos in any of the forms of this function.
By default, the position of the first character in the string from which the substring is to be extracted is reckoned as 1. For , when sql_mode is set to 'oracle', position zero is treated as position 1 (although the first character is still reckoned as 1).
If any argument is NULL, returns NULL.
The optimizer can take advantage of queries of the format .
The optimizer cannot take advantage of queries of the format .
Oracle mode:
- Returns the position of a string within a string
- Returns the position of a string within a string
- Returns a string based on substring
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SUBSTRING(str,pos),
SUBSTRING(str FROM pos),
SUBSTRING(str,pos,len),
SUBSTRING(str FROM pos FOR len)
SUBSTR(str,pos),
SUBSTR(str FROM pos),
SUBSTR(str,pos,len),
SUBSTR(str FROM pos FOR len)SELECT SUBSTRING('Knowledgebase',5);
+------------------------------+
| SUBSTRING('Knowledgebase',5) |
+------------------------------+
| ledgebase |
+------------------------------+
SELECT SUBSTRING('MariaDB' FROM 6);
+-----------------------------+
| SUBSTRING('MariaDB' FROM 6) |
+-----------------------------+
| DB |
+-----------------------------+
SELECT SUBSTRING('Knowledgebase',3,7);
+--------------------------------+
| SUBSTRING('Knowledgebase',3,7) |
+--------------------------------+
| owledge |
+--------------------------------+
SELECT SUBSTRING('Knowledgebase', -4);
+--------------------------------+
| SUBSTRING('Knowledgebase', -4) |
+--------------------------------+
| base |
+--------------------------------+
SELECT SUBSTRING('Knowledgebase', -8, 4);
+-----------------------------------+
| SUBSTRING('Knowledgebase', -8, 4) |
+-----------------------------------+
| edge |
+-----------------------------------+
SELECT SUBSTRING('Knowledgebase' FROM -8 FOR 4);
+------------------------------------------+
| SUBSTRING('Knowledgebase' FROM -8 FOR 4) |
+------------------------------------------+
| edge |
+------------------------------------------+SELECT SUBSTR('abc',0,3);
+-------------------+
| SUBSTR('abc',0,3) |
+-------------------+
| |
+-------------------+
SELECT SUBSTR('abc',1,2);
+-------------------+
| SUBSTR('abc',1,2) |
+-------------------+
| ab |
+-------------------+
SET sql_mode='oracle';
SELECT SUBSTR('abc',0,3);
+-------------------+
| SUBSTR('abc',0,3) |
+-------------------+
| abc |
+-------------------+
SELECT SUBSTR('abc',1,2);
+-------------------+
| SUBSTR('abc',1,2) |
+-------------------+
| ab |
+-------------------+