FROM 子句以及 JOIN、APPLY、PIVOT (Transact-SQL).pdf
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FROM ⼦句以及 JOIN、APPLY、PIVOT
(Transact-SQL)
项⽬
2023/05/24
24 个参与者
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本文内容 语法 ⾃变量 备注 使⽤ APPLY 显⽰另外 5 个
适⽤于： SQL Server 2016 (13.x) 及更⾼版本 Azure SQL 数据库 Azure SQL 托管实例
Azure Synapse Analytics Analytics Platform System (PDW) Microsoft Fabric 中的 SQL
分析终结点 Microsoft Fabric 中的仓库
在 Transact-SQL 中，FROM ⼦句在以下语句中可⽤：
DELETE
UPDATE
SELECT
SELECT 语句通常需要使⽤ FROM ⼦句。 当没有列出表列以及列出的唯⼀项是文本或变量或算术
表达式时除外。
本文还讨论了可以在 FROM ⼦句中使⽤的以下关键字：
JOIN
APPLY
PIVOT
Transact-SQL 语法约定
语法
SQL Server 和 Azure SQL 数据库的语法：
syntaxsql复制
[ FROM { <table_source> } [ , ...n ] ]
<table_source> ::=
{
table_or_view_name [ FOR SYSTEM_TIME <system_time> ] [ [ AS ] table_alias ]
[ <tablesample_clause> ]
[ WITH ( < table_hint > [ [ , ] ...n ] ) ]
| rowset_function [ [ AS ] table_alias ]
[ ( bulk_column_alias [ , ...n ] ) ]
| user_defined_function [ [ AS ] table_alias ]
| OPENXML <openxml_clause>
| derived_table [ [ AS ] table_alias ] [ ( column_alias [ , ...n ] ) ]
| <joined_table>
| <pivoted_table>
| <unpivoted_table>
| @variable [ [ AS ] table_alias ]
| @variable.function_call ( expression [ , ...n ] )
[ [ AS ] table_alias ] [ (column_alias [ , ...n ] ) ]
}
<tablesample_clause> ::=
TABLESAMPLE [ SYSTEM ] ( sample_number [ PERCENT | ROWS ] )
[ REPEATABLE ( repeat_seed ) ]
<joined_table> ::=
{
<table_source> <join_type> <table_source> ON <search_condition>
| <table_source> CROSS JOIN <table_source>
| left_table_source { CROSS | OUTER } APPLY right_table_source
| [ ( ] <joined_table> [ ) ]
}
<join_type> ::=
[ { INNER | { { LEFT | RIGHT | FULL } [ OUTER ] } } [ <join_hint> ] ]
JOIN
<pivoted_table> ::=
table_source PIVOT <pivot_clause> [ [ AS ] table_alias ]
<pivot_clause> ::=
( aggregate_function ( value_column [ [ , ] ...n ] )
FOR pivot_column
IN ( <column_list> )
)
<unpivoted_table> ::=
table_source UNPIVOT <unpivot_clause> [ [ AS ] table_alias ]
<unpivot_clause> ::=
( value_column FOR pivot_column IN ( <column_list> ) )
<column_list> ::=
column_name [ , ...n ]
<system_time> ::=
{
AS OF <date_time>
| FROM <start_date_time> TO <end_date_time>
| BETWEEN <start_date_time> AND <end_date_time>
| CONTAINED IN (<start_date_time> , <end_date_time>)
| ALL
}
<date_time>::=
of 25
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