INSERT [INTO] table_name [table_column_list] VALUES (data_value_list) INTO是可以省略的。 table_column_list建议都显式给出,一是增强可读性,二是以后即使是表的结构发生改变,也不会有所影响。 2. INSERT INTO ... SELECT语句 批量插入数据。 INSERT [INTO] <表名> [<列表名>] <SELECT 语句> 三、...
CREATE VIEW View1 AS SELECT Colx, Coly FROM TableA, TableB WHERE TableA.ColZ = TableB.Colz; 查詢計畫中的聯結順序為 Table1、 Table2、 TableA、 TableB、 Table3。解析檢視表上的索引對於任何索引,只有在查詢最佳化工具認為有所助益時,SQL Server 才會選擇在其查詢計畫中使用索引檢視表。所有...
在Transact-SQL 中,FROM 子句在以下语句中可用: 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 ...
or materialized views. Oracle Database performs a join whenever multiple tables appear in the FROM clause of the query. The select list of the query can select any columns from any of these tables. If any two of these tables have a column name in common, then you must qualify all referen...
SELECT s.name AS statistics_name ,c.name AS column_name ,sc.stats_column_id FROM sys.stats AS s INNER JOIN sys.stats_columns AS sc ON s.object_id = sc.object_id AND s.stats_id = sc.stats_id INNER JOIN sys.columns AS c ON sc.object_id = c.object_id AND c.column_id = sc...
SELECT-- C.4p.nameAS[Package], c.object_nameAS[Event], c.nameAS[Column-for-Predicate-Data], c.descriptionAS[Column-Description]FROMsys.dm_xe_object_columnsAScJOINsys.dm_xe_objectsASoONo.name = c.object_nameJOINsys.dm_xe_packagesASpONp.guid = o.package_guidWHEREc.column_type ='data'...
DECLARE tables_cursor CURSOR FOR SELECT s.name, t.name FROM sys.objects AS t INNER JOIN sys.schemas AS s ON s.schema_id = t.schema_id WHERE t.type = 'U'; OPEN tables_cursor; DECLARE @schemaname AS sysname; DECLARE @tablename AS sysname; FETCH NEXT FROM tables_cursor INTO @schema...
每种join 都有on , on的是左表和右表中都有的字段。join 之前要确保关联键是否去重,是不是刻意保留非去重结果。 3. 两张表数据的字段一样,想合并起来,怎么办? -- 不去重,合并两张表的数据select*from(selectidfromtable_1UNIONALLselectidfromtable_2)t; ...
SELECT * FROM table1 AS a RIGHT [OUTER] JOIN ON a.column=b.column 3)全外连接full [outer] join 显示符合条件的数据行,同时显示左右不符合条件的数据行,相应的左右两边显示NULL,即显示左连接、右连接和内连接的并集。 一、交叉连接(cross join) ...
A SQL equijoin (also known as a natural or semijoin) creates a relationship between two tables based on a comparison of values found in one or a set of columns in one table and one or an equal set of columns in another table.