Oracle语句整理（Oracle statement finishing）.doc

Oracle语句整理（Oracle statement finishing） DQL database query language The select A simple query Select * [field...] From the name of the table; Single conditional query Select * [fields...] From table name where conditions; Many conditions Select * [field...] From table name where condition and condition or condition; The sorting Select * [field...] From table name where condition and condition or condition or condition order by field asc (default) ascending/desc descending order, field asc/desc... ; Note: order by must be written after where grouping Select * [field...] From table name where condition and condition or condition group by field, field... Having conditions and conditions or conditions... ; Note: group by must be written after where The subquery Single line subquery Single condition Select * [field...] From table name where condition = ( Select * [field...] From the table name where conditions and conditions or conditions; Many conditions Select * [field...] (condition 1, condition 2,...) ( Select field 1, field 2,... From the table name where conditions and conditions or conditions; Note: the fields in the subquery must be consistent with the conditions Multiline query Select * [fields...] From table name where condition key ( Select * [field...] From the table name where conditions and conditions or conditions; Note: keywords are in the knowledge point file The result set is used as the query object Select * [fields...] From (select * [field...] the where condition and condition or condition of the from table name and condition or condition) Branch query The select field, Case [field] When [value] condition then the value of the expression When [value] condition then the value of the expression When [value] condition then the value of the expression ...... The value of the expression can be omitted when the above conditions are inconsistent End, field,... From the name of the table; -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --