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子查询

网络Subquery; Sub-Queries; EXISTS

子查询

网络释义

子查询

Subquery

称为子查询（subquery）。答案补充换句话说，子查询可以出现在语句的好多地方，出现在where后也可以，from后也可以，判 …

Sub-Queries

子查询 (Sub-queries)伺服器端游标 (Server-side cursors) 查询快取 (Query caching) 资料库封锁 (Locking of databases) 较好的 …

EXISTS

SQL server 2005 的简单语句_百度知道 ... Select ... From 字段1=(子查询) Exists 子查询 If (子查询) ...

as subquery

将子查询(as subquery)或in或exists当成where的一个条件的一部分,这样的查询称为子查询 .where中可以包含一个select语句的 …

sub-select

...程序而且支持事务处理(trans-action)、子查询(sub-select)，过程(procedure)、自定义函数(function)、光标(cursor)，支持了大 …

Sub-SELECTs

●介绍常见的SQL语法及相关范例，并说明新版子查询(Sub-SELECTs)上的支援●说明支援Unicode 以及其他字元集，和INFOR…

in

SQL Server T-SQL高级查询 - hoojo - 博客园 ... --like 模糊查询 --in 子查询 --not in 不在其中 ...

correlated subquery

...、分组(group)、函数 (function)、子查询(correlated subquery)、联合(union)等等。

例句：

The previous restrictions apply to any subqueries in the FROM clause of the view , just as they apply to the view itself .

上述限制适用于视图的 FROM 子句中的任何子查询，就像其应用于视图本身一样。

Within the body of a subquery , it is often necessary to refer to the value of a column in the active row of the main query .

在子查询的正文中，通常需要引用主查询的活动行中的列的值。

The inner-most sub-select identifies all rows that need to be updated ; the user might have given some conditions to restrict the rows .

最里边的子查询找出所有需要更新的行；用户可能已经给出了一些条件来限制这些行。

The EXISTS condition is TRUE if the subquery result contains at least one row , and FALSE if the subquery result does not contain any rows.

如果子查询结果至少包含一行，则 EXISTS 条件为 TRUE ；如果子查询结果一行也不包含，则条件为 FALSE 。

The uncorrelated subqueries do not rely on the main query for information ; hence they increase the power and flexibility of your main query .

不相关的子查询不依靠主查询来获取信息；因此，它们增加了主查询的能力和灵活性。

Number of optimizations for a query that contains at least one subquery.

包含至少一个子查询的查询的优化数。

Two types of queries can be used in the WHERE clause of an UPDATE statement : a scalar subquery and a table subquery.

两种查询可以用于 UPDATE 语句的 WHERE 子句中：标量子查询和表子查询。

The IN operator is one of four SQL operators that you can use with a table subquery .

IN 操作符是可以用于表子查询的四个 SQL 操作符之一。

If the subquery (which must have one column ) returns one row, then the value of that row is compared to the expression .

如果子查询（必须含有一列）返回一行，则该行的值将与表达式进行比较。

Casts may be required if the columns of the initial subquery do not have the same domains as those of the recursive subquery .

如果初始子查询的列与递归子查询的列具有不同的域，则可能需要进行转换。

Is a constant , function , any combination of column names, constants, and functions connected by an operator or operators, or a subquery .

常量、函数以及由一个或多个运算符连接的列名、常量和函数的任意组合，或者是子查询。

The query above contains a correlated subquery, since the main query and the subquery are relaying on the same table , the employees table.

以上查询包含一个相关子查询，因为主查询和子查询依靠于同一个表，即 employees 表。

The main query does not contain a GROUP BY clause, and is not an aggregate query, or the subquery returns exactly one value .

主查询不包含 GROUPBY 子句并且不是汇总查询，或者子查询恰好返回一个值。

The number of times the subquery and its function is executed can vary with different access paths chosen by the optimizer .

子查询及其函数执行的次数会因优化器选择的访问路径的不同而异。

Total number of rows processed by the SQL statement . This total does not include rows processed by subqueries of the SQL statement.

sql 语句处理的总行数。这个总行数不包括子查询处理的行数。

The first is the unnesting of the subquery into a join between the employee and sales_order tables .

第一个优化解除了职员与 sales_order 表之间连接中的子查询嵌套。

This extension , specifying a join, can be used instead of a subquery in the WHERE clause to identify rows to be removed .

这个扩展指定联接，可在 WHERE 子句中取代子查询来标识要删除的行。

The database server automatically attempts to convert the values returned by the recursive subquery to match those of the initial query .

数据库服务器会自动尝试转换由递归子查询返回的值，以便与初始查询的那些值匹配。

In this case , error 1242 means that the query execution failed because there was a problem in a subquery.

在这里，错误 1242 表示查询操作失败，由于子查询有问题。

The previous subquery in this statement cannot be evaluated independently of the outer query .

该语句中前面的子查询无法独立于外部查询进行计算。

The only change we made here was to get rid of the subquery in the original qeury.

这里我们所做的惟一更改就是去掉了原始查询中的子查询。

The SQL fragment can be as complex as you want avec even includesubselects .

SQL 片段可以是任意复杂的，甚至可包含子查询。

子查询

子查询