Loops that iterate over SQL query results are quite common, both in application programs that run outside the DBMS, as well as User Defined Functions (UDFs) and stored procedures that run within the DBMS. It can be argued that set-oriented operations are more efficient and...
Loops that iterate over SQL query results are quite common, both in application programs that run outside the DBMS, as well as User Defined Functions (UDFs) and stored procedures that run within the DBMS. It can be argued that set-oriented operations are more efficient and should be ...
(2)解析游标(dbms_sql.parse) Parse cursor: A SQL statement is associated with thecursor. Its parsed representation that includes the execution plan (whichdescribes how the SQL engine will execute the SQL statement) is loaded in theshared pool, specifically, in the library cache. The structure i...
首先,session1执行以下匿名块,该匿名块通过cursor取得t1表的所有数据,不过在open cursor后将暂停30秒,在这30秒中我们将在session2中删除t1表的所有数据: DECLARE CURSOR c IS SELECT deptno ,dname ,loc FROM t1; TYPE dept_tab IS TABLE OF c%ROWTYPE; l_depts dept_tab; BEGIN dbms_output.put_line('op...
(5)Physicaloptimization: During this phase, several operations areperformed. At first, the execution plans related to each SQL statementresulting from the logical optimization are generated. Then, based onstatistics found in the data dictionary or gathered through dynamic sampling, acost is associated...
40, OPERATIONS, BOSTON 由于在22:35:25我们就已经打开了游标,所以结果依然能输出t1表的所有数据,尽管在22:35:35之前我们已经删除了t1表的所有数据并提交,而cursor取数据(fetch)发生在22:35:55之后。 ref: The OPEN statement executes the query associated with a cursor. It allocates database resources to...
0: All DBMS_SQL operations are allowed on the cursor without any security checks. 1: The effective_user_id value of a BIND or EXECUTE caller must be the same as the effective_user_id value of the last PARSE caller. 2: The effective_user_id value of a BIND, EXECUTE, DEFINE, DESCRIBE...
dbms_xplan.display_cursor 1) sql tunning asking01 Note: example for reading execution plan, dbms_xplan.display_cursor('sql_id',child_number,'mode') 1@@@ sql script [oracle@station78 ~]$ sqlplus / as sysdba; SQL*Plus: Release 11.2.0.1.0 Production on Sun Mar 3 13:48:02 2013 ...
The implicit cursors are allocated by Oracle by default while executing SQL statements. It holds the affected rows by the DML operations like UPDATE, DELETE and INSERT. Thus implicit cursors are used when we don’t have an explicit cursor in place. ...
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