mysql>helpunionSyntax:SELECT...UNION[ALL|DISTINCT]SELECT... [UNION[ALL|DISTINCT]SELECT...] 第一个select语句的column_name会被当做最后查询结果的列名,接下来的每个select语句所一一对应的列应该和第一个语句的列的数据类型最好保持一致 默认情况下union语句会把最终结果中的重复行去掉,这和增加distinct这个关键...
SELECTName:'SELECT'Description: Syntax:SELECT[ALL | DISTINCT | DISTINCTROW][HIGH_PRIORITY][STRAIGHT_JOIN][SQL_SMALL_RESULT][SQL_BIG_RESULT][SQL_BUFFER_RESULT]SQL_NO_CACHE[SQL_CALC_FOUND_ROWS]select_expr[, select_expr ...][FROM table_references [PARTITION partition_list][WHERE where_condition]...
因为表名有空格 create table student_info(...); #其中order使用``飘号,因为order和系统关键字或系统函数名等预定义标识符重名了 CREATE TABLE `order`( id INT, lname VARCHAR(20) ); select id as "编号", `name` as "姓名" from t_stu; #起别名时,as...
SELECTfirst_nameASnameFROMCustomers; Run Code Here, the SQL command selects thefirst_namecolumn from the Customers table. However, the column name is changed to name in the result set. SQL AS Alias Syntax The syntax of the SQLAScommand is: SELECTcolumn_1ASalias_1, column_2ASalias_2, ....
SQL keywords are NOT case sensitive:selectis the same asSELECT In this tutorial we will write all SQL keywords in upper-case. Semicolon after SQL Statements? Some database systems require a semicolon at the end of each SQL statement. ...
SQL syntax問題1）'Customer' As Type与'Supplier'是为了区分Customers与Suppliers这2张表中的记录，不然...
3.1 select Select * from datatype; SQL Advisor审核建议 2018-07-27 15:12:22 26936 [Note] 第1步: 对SQL解析优化之后得到的SQL:select `*` AS `*` from `testdb`.`datatype` 2018-07-27 15:12:22 26936 [Note] 第2步:表datatype 的SQL太逆天,没有优化建议 ...
SELECTidentifier_column,pivot_column,value_columnFROMtable_nameUNPIVOT(value_columnforpivot_columnIN([column1],[column2],...,[columnN]))ASunpivot_table; 其中,identifier_column是唯一标识每个转换后的行的列,pivot_column是需要将其转换为行的列,value_column是转换后的列的值。例如,假设我们有一个表格记...
syntaxsql 复制 SELECT [ ALL | DISTINCT ] [ TOP ( expression ) [ PERCENT ] [ WITH TIES ] ] <select_list> <select_list> ::= { * | { table_name | view_name | table_alias }.* | { [ { table_name | view_name | table_alias }. ] { column_name | $IDENTITY | $ROWGUID }...
USE AdventureWorks2022; GO SELECT AVG(UnitPrice) AS [Average Price] FROM Sales.SalesOrderDetail; column_alias可用在 ORDER BY 子句中。 不過,它不能用在 WHERE、GROUP BY 或 HAVING 子句中。 如果查詢運算式是 DECLARE CURSOR 陳述式的一部分,column_alias 就不能用在 FOR UPDATE 子句中。 備註 為選取...