sqlupdate如何多表关联更新？（代码示例）

在本例中：我们要用表gdqlpj中的gqdltks，bztks字段数据去更新landleveldata中的同字段名的数据，条件是当landleveldata 中的GEO_Code字段值与gdqlpj中的lxqdm字段值相等时进行更新。

SQL Server语法:

UPDATE { table_name WITH ( < table_hint_limited > [ ...n ] ) |view_name | rowset_function_limited } SET { column_name = { expression | DEFAULT| NULL } | @variable = expression | @variable = column = expression } [ ,...n ]
{ { [ FROM { < table_source > } [ ,...n ] ] [ WHERE < search_condition > ] } | [
WHERE CURRENT OF { { [ GLOBAL ] cursor_name } | cursor_variable_name } ] } [
OPTION ( < query_hint > [ ,...n ] ) ]

SQL Server示例:

update a set a.gqdltks=b.gqdltks,a.bztks=b.bztks from
landleveldata a,gdqlpj b where a.GEO_Code=b.lxqdm

Oracle语法:

UPDATE updatedtable SET (col_name1[,col_name2...])= (SELECT
col_name1,[,col_name2...] FROM srctable [WHERE where_definition])

Oracel 示例:

update landleveldata a set (a.gqdltks, a.bztks)= ( b.gqdltks,
b.bztks from gdqlpj b where a.GEO_Code=b.lxqdm)

MySQL语法:

UPDATE table_references SET col_name1=expr1 [, col_name2=expr2 ...]
[WHERE where_definition]

MySQL 示例:

update landleveldata a, gdqlpj b set a.gqdltks= b.gqdltks, a.bztks=
b.bztks where a.GEO_Code=b.lxqdm