3
SQL Expressions
This chapter presents the syntax for combining values, operators, and functions into expressions.
This chapter includes the following section:
■Syntax for SQL Expression Types
Syntax for SQL Expression Types
An expression is a combination of one or more values, operators, and SQL functions that evaluate to a value. An expression generally assumes the datatype of its components.
Expressions have several forms. Table 3–1 shows the syntax for each form of expression. Refer to Chapter 5, "Subclauses" for the syntax of the subclauses found in the following table.
See Also: Expressions in Oracle Database SQL Reference for detailed information about SQL expressions
Table 3–1 Syntax for SQL Expression Types
SQL Expression Type |
Syntax |
|
|
|
|
CASE expression |
CASE { |
simple_case_expression |
|
| |
searched_case_expression |
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} |
|
|
[ |
else_clause ] |
|
END |
|
SQL Expressions 3-1
Syntax for SQL Expression Types
Table 3–1 (Cont.) Syntax for SQL Expression Types
SQL Expression Type |
Syntax |
|
|
|
|
Compound expression |
{ (expr) |
|
|
| { + | - | PRIOR } expr |
|
|
| expr { * | / | + | - | || } expr |
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|
} |
|
|
Note: The double vertical bars are part of the syntax |
|
|
(indicating concatenation) rather than BNF |
|
|
notation. |
|
CURSOR expression |
CURSOR (subquery) |
|
DATETIME expression |
datetime_value_expr AT |
|
|
{ LOCAL |
|
|
| TIME ZONE { ' [ + | - ] hh:mm' |
|
|
| DBTIMEZONE |
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|
| 'time_zone_name' |
|
|
| expr |
|
|
} |
|
|
} |
|
Function expression |
any built-in SQL function or user-defined function can be |
|
|
used as an expression |
|
INTERVAL expression |
interval_value_expr |
|
|
{ DAY [ (leading_field_precision) ] TO |
|
|
SECOND [ (fractional_second_precision) ] |
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| YEAR [ (leading_field_precision) ] TO |
|
|
MONTH |
|
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} |
|
Model expression |
{ measure_column | aggregate_funtion } |
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|
[ { condition | expr } |
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|
[ , { condition | expr } ]... |
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|
] |
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Note: The outside square brackets are part of the syntax. |
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|
In this case, they do not represent optionality. |
|
Object access expression |
{ table_alias.column. |
|
|
| object_table_alias. |
|
|
| (expr). |
|
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} |
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|
{ attribute [.attribute ]... |
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[.method ([ argument [, argument ]... |
]) ] |
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| method ([ argument [, argument ]... ]) |
|
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} |
|
Scalar subquery expression |
a subquery that returns exactly one column value from one |
|
|
row can be used as an expression |
|
3-2 Oracle Database SQL Quick Reference
Syntax for SQL Expression Types
Table 3–1 (Cont.) Syntax for SQL Expression Types
SQL Expression Type |
Syntax |
|
|
Simple expression |
{ [ query_name. |
|
| [schema.] |
|
{ table. | view. | materialized view. } |
|
] { column | ROWID } |
|
| ROWNUM |
|
| text |
|
| number |
|
| sequence. { CURRVAL | NEXTVAL } |
|
| NULL |
|
} |
Type constructor expression |
[ NEW ] [ schema. ]type_name |
|
([ expr [, expr ]... ]) |
Variable expression |
:host_variable |
|
[ [ INDICATOR ] |
|
:indicator_variable |
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] |
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SQL Expressions 3-3
Syntax for SQL Expression Types
3-4 Oracle Database SQL Quick Reference