SELECT TOP 2 * FROM Customers; SQL SELECT TOP PERCENT 实例 下面的 SQL 语句从 “Customers” 表中选取前面 50% 的记录: SELECT TOP 50 PERCENT * FROM Customers;
代码语言:sql 复制 删除Customers 表: DROP TABLE Customers; SQL TOP、LIMIT、FETCH FIRST 或 ROWNUM 子句 SQL SELECT TOP 子句用于指定要返回的记录数。 SQL SELECT TOP 子句 SQL Server / MS Access 语法: 代码语言:sql 复制 SELECT TOP number|percent column_name(s) FROM table_name WHERE condition; MyS...
在SELECT语句中,应始终将一个ORDER BY子句与该TOP子句一起使用,以指定哪些行受过TOP滤器影响。如果您需要实现一个应用程序窗口小部件寻呼解决方案,送块或数据到客户端的“页面”,所以用户可以通过滚动数据,它是更好,更容易使用OFFSET-FETCH节中ORDER BY节,而不是TOP条款。 SQL Prompt(BP006)中的“最佳实践”代码...
but they can be in different conditions. For example, (PRIOR a = level) is not allowed, but (PRIOR a = b) and (level = 1) is allowed. Different conditions refer to the conditions connected by AND at the top of the CONNECT BY ...
If the query in which you specify this clause is not a top-level SELECT statement, then the following rules apply to the top-level SQL statement that contains the query: If the top-level statement is a SELECT statement, then it must have either a WITH plsql_declarations clause or the ...
Oracle Database Application Developer's Guide - FundamentalsandPL/SQL Packages and Types Referencefor information about session-level Flashback using theDBMS_FLASHBACKpackage Oracle Database Administrator's Guideand to the description ofFLASHBACK_TRANSACTION_QUERYin theOracle Database Referencefor more inf...
SQL Copy SELECT * FROM <table_name_1> WHERE (column_name_1, column_name_2) IN (SELECT column_name_1, column_name_2 FROM <table_name_2>;) The following table and dataset were used for the examples SQL Copy CREATE TABLE assets( asset_id INT, asset_type VARCHAR(50), asset_desc VAR...
When you create temporary tables, you won’t see them in the current database you’re working on. SQL Server puts them into TempDB. Let’s try it using the previous example: USE AdventureWorks; GO SELECT a.ProductID ,a.Name as ProductName ...
6:TOP 7:GROUP BY 7.1:GROUP BY ALL 7.2:HAVING 8:SELECT字句技术 8.1:使用DISTINCT消除重复值 8.2:返回拼接的结果 8.3使用INTO字句 9:子查询 9.1:子查询类型 9.2:代替表达式的查询 9.3:多层嵌套 10:比较使用 EXISTS 和 IN 的查询 11:联接 11.1:使用衍生表 ...
不同的数据库生产厂商都支持SQL语句,但都有特有内容。 1.2 SQL语言排行榜 自从SQL 加入了 TIOBE 编程语言排行榜,就一直保持在 Top 10。 1.3 SQL 分类 SQL语言在功能上主要分为如下3大类: DDL(Data Definition Languages、数据定义语言),这些语句定义了不同的数据库、表、视图、索引等数据库对象,还可以用来创建...