LEFT JOIN vs. LEFT OUTER JOIN in SQL Server As per the documentation:FROM (Transact-SQL): <join_type>::=[ {INNER|{ {LEFT|RIGHT|FULL} [OUTER] } } [<join_hint>] ]JOIN The keywordOUTERis marked as optional (enclosed in square brackets). In this specific case, whether you specifyOUTE...
As per the documentation:FROM (Transact-SQL): <join_type> ::= [ { INNER | { { LEFT | RIGHT | FULL } [ OUTER ] } } [ <join_hint> ] ] JOIN 1. 2. 3. The keywordOUTERis marked as optional (enclosed in square brackets). In this specific case, whether you specifyOUTERor not ...
SQL OUTER JOIN – right outer join SQL right outer join returns all rows in the right table and all the matching rows found in the left table. The syntax of the SQL right outer join is as follows: SELECTcolumn1, column2...FROMtable_ARIGHTJOINtable_BONjoin_conditionWHERErow_conditionCode...
The NATURAL [LEFT] JOIN of two tables is defined to be semantically equivalent to an INNER JOIN or a LEFT JOIN with a USING clause that names all columns that exist in both tables. # RIGHT JOIN works analogously to LEFT JOIN. To keep code portable across databases, it is recommended that...
SQL LEFT JOIN, also known as a LEFT OUTER JOIN, is a type of SQL JOIN operation that retrieves all records from the left table (table1) and the matching records from the right table (table2). If there are no matching records in the right table, NULL values are included for those co...
Visual presentation of SQL Left Join: Left Join: Syntax SELECT * FROM table1 LEFT [ OUTER ] JOIN table2 ON table1.column_name=table2.column_name; SELECT:Specifies the columns or all columns to be included in the result. FROM table1:Specifies the left table in the join. ...
Visual presentation of SQL Left Join: Left Join: Syntax SELECT * FROM table1 LEFT [ OUTER ] JOIN table2 ON table1.column_name=table2.column_name; SELECT:Specifies the columns or all columns to be included in the result. FROM table1:Specifies the left table in the join. ...
Join the left table with the right table and return all joined records of the left table. If no joined record is found, NULL will be returned.LEFT OUTER JOIN: Returns all
这两个应该就是一样的吧。left join是left outer join的简写。你可以用explain extended和show warnings看到数据库优化改写之后的语句,两个SQL是一样的。 有用1 回复 查看全部 2 个回答 推荐问题 php用这种方法做json接口合适不? 一个php文件做前端的接口,这样来请求数据的写法合适吗?大致就是:我使用了一个Mysq...
SQL Reference Guide A Left Outer Join (LOJ) is one of the join operations that allows you to specify a join clause. It preserves the unmatched rows from the first (left) table, joining them with a NULL row in the second (right) table. This means all left rows that do not have a ...