CTE_query_definition:指定一个其结果集填充公用表表达式的 SELECT 语句。 三.SELECT…FROM子句 SELECT表明要读取信息,FROM指定要从中获取数据的一个或多个表的名称。SELECT…FROM就够成了一个基本的查询语句。 语法如下: SELECT [ ALL | DISTINCT ] [ TOP expression [ PERCENT ] [ WITH TIES ] ] <select_l...
SET @Variable1 = expression1, @Variable2 = expression2, ...; 例如: 代码语言:sql 复制 DECLARE @Var1 INT = 10; DECLARE @Var2 INT = 20; SET @Var1 = @Var1 + 5, @Var2 = @Var2 - 5; SELECT @Var1 AS 'Var1', @Var2 AS 'Var2'; 使用UPDATE语句更新多个变量: 代码语言:sql ...
T-SQL与MySQL的SELECT语法差异 主要体现在以下几个方面: 语法结构差异: T-SQL使用方括号([])来引用对象名称,而MySQL使用反引号(`)。 T-SQL中使用TOP关键字来限制返回的记录数,而MySQL使用LIMIT关键字。 T-SQL中使用方括号([])来引用字符串,而MySQL使用单引号(')。 函数差异: T-SQL和MySQL都支持常用的聚合...
SELECT @nIndexID = indid FROM sysindexes WHERE id = @nTableID AND indid BETWEEN 1 And 254 AND (status & 2048) = 2048 ORDER BY indid IF (@nIndexID Is Null) RETURN 0 We now assign the Index ID of the table's primary key index to the variable @nIndexID. The twelfth bit (2048...
selectcount(*)fromstudent;selectcount(sex)fromstudent;selectcount(distinctsex)fromstudent; –top 取前N条记录 selecttop3*fromstudent; –alias column name 列重命名 selectidas编号, name'名称', sex 性别fromstudent; –alias table name 表重命名 ...
you must enclose it in parentheses. The expression should be of the BIGINT datatype when not using the PERCENT option, and a float value in the range 0 through 100 when using the PERCENT option. The following code shows how to use an expression with a variable to return the requested num...
@variable_name 查询中使用的局部变量的名称,可以将值分配给该变量以用于OPTIMIZE FOR查询提示。 UNKNOWN 指定查询优化器在查询优化期间使用统计数据而不是初始值来确定局部变量的值。 literal_constant 要分配@variable_nameOPTIMIZE FOR用于查询提示的文本常量值。literal_constant 只在查询优化期间使用,在查询执行期间不...
SelectSetVariable.Accept(TSqlFragmentVisitor) Method Reference Feedback Definition Namespace: Microsoft.SqlServer.TransactSql.ScriptDom Assembly: Microsoft.SqlServer.TransactSql.ScriptDom.dll Package: Microsoft.SqlServer.TransactSql.ScriptDom v161.8901.0 Accepts visitor C# 复制 public override void...
Get the comma separated value and assign to other variable using sql server Get the Execution Plan of an SPID get the half of the year (like quarter) Get the last inserted uniqueidentifier field Get the quarter of a given date in datetime format Get the TOP 1 of a Select Distinct Get th...
Feature Inline table variable declarations. Table variables must reference explicitly defined memory-optimized table types. You should create a memory-optimized table type and use that type for the variable declaration, rather than specifying the type inline. Feature Disk-based tables Disk-based tables...