Search for particular conditions
WEHRE LIKE BETWEEN IN ON OR …………
UNION keyword
A plurality of row-level process tables together
SELECT expression1, expression2, ... expression_n
FROM tables
[WHERE conditions]
UNION [ALL | DISTINCT]
SELECT expression1, expression2, ... expression_n
FROM tables
[WHERE conditions];
参数说明
expression1, expression2, ... expression_n: to retrieve the column.
tables: to retrieve the data table.
WHERE conditions: optional search condition.
DISTINCT: Optional, delete duplicate the results of the data set. By default, the UNION operator has removed the duplicate data, so the impact on the results DISTINCT modifier nothing.
ALL: Alternatively, return all the result sets that contain duplicate data.
ORDER BY ordering
Packet GORUP BY + HAVING
DISTINCT filter
Join Query SQL92 / SQL99
The only difference: outer join
left outer join LEFT JOIN
right outer join RIGHT JOIN
paging query
Original
the SELECT the FROM
(the SELECT ROWNUM the NUT, the FROM T.
(The FROM the EMP the ORDER BY the SELECT SAL) the WHERE ROWNUM T <10)
the WHERE NU>. 5;
now
SELECT FROM EMP LIMIT 1,10;
wherein SELECT * FROM EMP LIMIT N, M ; N M represents the starting position there are several representative of a record;