search-condition :
expression comparison-operator expression
| expression comparison-operator { [ ANY | SOME ] | ALL } ( subquery )
| expression IS [ NOT ] DISTINCT FROM expression
| expression IS [ NOT ] NULL
| expression [ NOT ] BETWEEN expression AND expression
| expression [ NOT ] LIKE pattern [ ESCAPE expression ]
| expression [ NOT ] SIMILAR TO pattern [ ESCAPE escape-expression ]
| expression [ NOT ] REGEXP pattern [ ESCAPE escape-expression ]
| expression [ NOT ] IN ( { expression , ... )
     | ( query-expression )
| NOT search-condition
| CONTAINS (column-name [,... ] , query-string )
| EXISTS ( query-expression )
| search-condition [ { AND | OR } search-condition ] [ ... ]
| ( search-condition )
| ( search-condition , estimate )
|  search-condition IS [ NOT ] { TRUE | FALSE | UNKNOWN }
| expression IS [ NOT ] OF ( [ ONLY ] type-name ,... )
| trigger-operation

comparison-operator :
=   
| >  
| <  
| >=  
| <=  
| <>  
| !=  
| !< 
| !>

trigger-operation :
INSERTING 
| DELETING
| UPDATING [ ( column-name-string ) ] 
| UPDATE( column-name )

Search conditions are used either to choose a subset of the rows from a table, or in a control statement such as an IF statement to determine control of flow.

In SQL, every condition evaluates as one of TRUE, FALSE, or UNKNOWN. This is called three-valued logic. The result of a comparison is UNKNOWN if either value being compared is the NULL value.

Rows satisfy a search condition only if the result of the condition is TRUE. Rows for which the condition is UNKNOWN or FALSE do not satisfy the search condition.

Subqueries form an important class of expression that is used in many search conditions.

The LIKE, SIMILAR TO, and REGEXP search conditions are very similar.

Must be connected to the database.

None.

• Expressions
• ALL search condition
• ANY and SOME search conditions
• BETWEEN search condition
• CONTAINS search condition
• EXISTS search condition
• LIKE search condition
• SIMILAR TO search condition
• REGEXP search condition
• Understand spatial data type syntax
• Three-valued logic
• NULL special value
• Subqueries in search conditions
• LIKE, REGEXP, and SIMILAR TO search conditions