Difference between revisions of "LIKE Predicate"
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==Purpose== | ==Purpose== | ||
Special predicate | Special predicate | ||
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==Syntax== | ==Syntax== | ||
<expression1> [NOT] LIKE <expression2> | <expression1> [NOT] LIKE <expression2> | ||
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==See Also== | ==See Also== | ||
| − | [[SQL INSERT|INSERT]], [[SQL Predicates|PREDICATES]], [[SQL SELECT|SELECT]], [[SQL UPDATE|UPDATE]] | + | [[SQL INSERT|INSERT]], [[SQL Predicates|PREDICATES]], [[REVERSE()]], [[SQL SELECT|SELECT]], [[SQL UPDATE|UPDATE]] |
| − | + | ||
==Description== | ==Description== | ||
LIKE is a special predicate to evaluate whether the specified <expression1> matches <expression2>. The <expression2> can contain the following wildcards: | LIKE is a special predicate to evaluate whether the specified <expression1> matches <expression2>. The <expression2> can contain the following wildcards: | ||
| − | + | {| class="wikitable" width="100%" | |
| − | + | ||
| − | {| class="wikitable" | + | |
!Operator||Description | !Operator||Description | ||
|- | |- | ||
| Line 24: | Line 19: | ||
|- | |- | ||
|} | |} | ||
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The optional NOT evaluates whether the specified <expression1> does not match <expression2>. | The optional NOT evaluates whether the specified <expression1> does not match <expression2>. | ||
| + | Note: to optimize WHERE <cExpression1> LIKE '%xxx' clauses, [[INDEX]] on the reverse character sequence of the relevant <cExpression1> using the [[REVERSE()]] function. | ||
==Example== | ==Example== | ||
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SELECT name, address, balance, cost*1.15; | SELECT name, address, balance, cost*1.15; | ||
FROM accounts; | FROM accounts; | ||
| − | WHERE paid_date < date() AND name LIKE "% | + | WHERE paid_date < date() AND name LIKE "%Inc"; |
ORDER BY name, paid_date | ORDER BY name, paid_date | ||
</code> | </code> | ||
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[[Category:Documentation]] | [[Category:Documentation]] | ||
[[Category:SQL]] | [[Category:SQL]] | ||
Latest revision as of 06:18, 13 April 2018
Contents
Purpose
Special predicate
Syntax
<expression1> [NOT] LIKE <expression2>
See Also
INSERT, PREDICATES, REVERSE(), SELECT, UPDATE
Description
LIKE is a special predicate to evaluate whether the specified <expression1> matches <expression2>. The <expression2> can contain the following wildcards:
| Operator | Description |
|---|---|
| _ | Any single character |
| % | Zero or more characters |
The optional NOT evaluates whether the specified <expression1> does not match <expression2>.
Note: to optimize WHERE <cExpression1> LIKE '%xxx' clauses, INDEX on the reverse character sequence of the relevant <cExpression1> using the REVERSE() function.
Example
SELECT name, address, balance, cost*1.15; FROM accounts; WHERE paid_date < date() AND name LIKE "%Inc"; ORDER BY name, paid_date
