select empno as "员工编号",ename as "员工名称",job as "职务" from emp; 例2:不使用as指定列别名 select empno "员工编号",ename "员工名称",job "职务" from emp; 1.1.6 显示不重复记录 distinct 在select语句中,可以使用distinct关键字限制在查询结果显示不重复的数据。 select distinct job from emp...
join_condition:ONconditional_expr|USING(column_list) 在MySQL中,join/inner join/cross join三者的作用是一样的; join语句中表别名的用法: SELECTt1.name, t2.salaryFROMemployeeASt1INNERJOINinfoASt2ONt1.name=t2.name;SELECTt1.name, t2.salaryFROMemployee t1INNERJOINinfo t2ONt1.name=t2.name; from...
SELECTA.column_name,B.column_nameFROMtable_nameA,table_nameBWHEREA.column_name=B.column_nameANDA...
/* target for SELECT INTO */ List *targetList; /* the target list (of ResTarget) */ List *fromClause; /* the FROM clause */ Node *whereClause; /* WHERE qualification */ List *groupClause; /* GROUP BY clauses */ Node *havingClause; /* HAVING conditional-expression */ List *wind...
如需詳細資訊,請參閱 Conditional Split Transformation。 複製資料行轉換自訂屬性 複製資料行轉換只有元件層級上所有資料流程元件通用的屬性。 下表描述的是複製資料行轉換之輸出資料行的自訂屬性。 所有屬性都是可讀寫的。 展開資料表 屬性名稱資料類型描述 copyColumnId 整數 從中複製輸出資料行之輸入資料...
declare @x xml declare @v varchar(20) set @v='FirstName' set @x=' <ROOT rootID="2"> <FirstName>fname</FirstName> <LastName>lname</LastName> </ROOT>' SELECT @x.query(' if ( sql:variable("@v")="FirstName" ) then /ROOT/FirstName else /ROOT/LastName ') ...
下面以“select a, b from item”为例说明简单select语句的解析过程,函数exec_simple_query调用pg_parse_query执行解析,解析树中只有一个元素。 (gdb) p *parsetree_list $47 = {type = T_List, length = 1, head = 0x7f5ff986c8f0, tail = 0x7f5ff986c8f0} ...
Fixes for multiple monitors with different display scaling (file selector, print dialogs, MDI window title bars, scrollbar width)Conditional sections could be displayed incorrectly in the Code ContentsDefine Connections and Select Connection tree was incorrect on a secondary display with different DPI ...
varselect=SQLSelect()select.columns=[...]select.tables=[...]select.predicate=... SQLDatabasecan be used to create fluent query builders for most of these query types. structPlanet:Codable{varid:Int,name:String}letdb:someSQLDatabase=...tryawaitdb.create(table:"planets").column("id",type...
set hive.stats.fetch.column.stats=true; set hive.stats.fetch.partition.stats=true; 1. 2. 3. 4. 笛卡尔积处理 需求:笛卡尔积操作,默认情况下是不允许使用的!底层使用一个ReduceTask来做。笛卡尔积实现方式如下: select a.*, b.* from a, b; ...