数据操纵语言,Data manipulation language,检称DML,主要包括检索(SELECT)、插入(INSERT)、更新(UPDATE)、删除(DELETE),是SQL的一个核心部分。一条DML将开始一个事务,接下来的DML都是同一事务中的语句,直到提交(COMMIT)或回滚(ROLLBACK)。下面我们来逐一介绍下ORACLE中的插入、更新、删除和合并(MERGE)的语法及实例解析。
The following SQL statement deletes the customer "Alfreds Futterkiste" from the "Customers" table: Example DELETE FROM Customers WHERE CustomerName='Alfreds Futterkiste'; The "Customers" table will now look like this: Delete All Records It is possible to delete all rows in a table without d...
恢复delete 的rows Whenrows are deletedinOracle the dataisnotactually removed. The rowissimplymarkedasdeletedandthe freespacecountersandpointers adjustedaccordingly. The statusofa rowisstoredinthe Row Header which occupies thefirst few bytesofeach row. 当row 被delete 的时候,实际上data 并没有被remove,...
CHECK OPTIONto indicate that Oracle Database prohibits any changes to the table or view that would produce rows that are not included in the subquery. When used in the subquery of a DML statement, you can specify this clause in a subquery in theFROMclause but not in subquery in theWHERE...
When we run this statement, it will delete all rows that have a product_name of Couch. In this example it will delete one row. This query will work in all variations of SQL: Oracle, SQL Server, MySQL, PostgreSQL, and more. You’ll get an output like this: 1 row(s) deleted. Here...
int delete_rows=10000; ... 1. CHAR类型数组变量 EXEC SQL for :delete_rows delete FROM table_name WHERE a= :a; 由于char对应于Oracle的char类型,因此若有空格,则此时char即使用memset初始化,但也会带有后面的空格,有可能造成delete时where a=:a由于空格不匹配无法删除,例如:a赋值为'a’,但数组长度是...
【PL/SQL】三种删除方式 Delete,Truncate,Drop 看完这章你会学习到以下内容: 它们的共同点 它们的不同点 相同点: 它们都可以删除数据,清理那些无关紧要,与业务无关的数据。 不同点: 1.语句方面 delete语句是dml,这个操作会放到rollback segement中,事务提交之后才生效;如果有相应的trigger,执行的时候将被触发....
19 rows selected. SQL> explain plan for delete from (select * from t1,t2 where t1.id=1 and t2.id=t1.id and t2.info='digoal'); Explained. SQL> select * from table(dbms_xplan.display); PLAN_TABLE_OUTPUT --- Plan hash value: 2064908203 ---...
In this post we'll start with a quick recap ofhow delete works. Then look at several alternatives you can use in Oracle Database to remove rows faster: Removing all the rows fast withtruncate Usingcreate-table-as-selectto wipe a large fraction of the data ...
ヒントの詳細は、Oracle Databaseパフォーマンス・チューニング・ガイドを参照してください。 例 この例では、Pro*C/C++の埋込みSQLプログラムにおけるDELETE文の使用方法を示します。 EXEC SQL DELETE FROM emp WHERE deptno = :deptno AND job = :job; EXEC SQL DECLARE emp_cursor CURSOR...