In Oracle, you are not restricted to creating indexes on only columns. You can create function-based indexes. Syntax The syntax for creating a function-based index in Oracle/PLSQL is: CREATE [UNIQUE] INDEX index
函数索引(Function-based indexes)只有在where条件使用了与索引中相同的基于相同列的函数时才起作用。duzz$scott@orcl>set autotrace on duzz$scott@orcl>create table t1 as select * from dept; Table created. Elapsed: 00:00:00.01 duzz$scott@orcl>create index loc_idx on t1(upper(loc)); Index crea...
0 redo size 533 bytes sent via SQL*Net to client 385 bytes received via SQL*Net from client 2 SQL*Net roundtrips to/from client 0 sorts (memory) 0 sorts (disk) 1 rows processed duzz$scott@orcl>select * from t1 where upper(loc)='DALLAS'; DEPTNO DNAME LOC --- --- --- 20 RESEA...
In a three column index we can see that the main index stores pointers to both the original table and the reference table on make, which in turn has pointers to the reference table on model. When the multicolumn index is accessed, the main portion of the index (the index on the first ...
1. Creating a Basic Index in PostgreSQL Write a PostgreSQL query to create a simple index on a column to speed up query lookups. Click me to see the solution 2. Creating a Unique Index in PostgreSQL Write a PostgreSQL query to create a unique index on a column to enforce uniqueness. ...
SQL> CREATE TABLE TEST(ID NUMBER(10), NAME VARCHAR2(64)); Table created. SQL> DECLARE I NUMBER; 2 BEGIN 3 FOR I IN 1..1000 LOOP 4 INSERT INTO TEST VALUES(I, LPAD('T', 60)); 5 END LOOP; 6 COMMIT; 7 END; 8 / PL/SQL procedure successfully completed. ...
SQL> CREATE TABLE TEST(ID NUMBER(10), NAME VARCHAR2(64)); Table created. SQL> DECLARE I NUMBER; 2 BEGIN 3 FOR I IN 1..1000 LOOP 4 INSERT INTO TEST VALUES(I, LPAD(‘T’, 60)); 5 END LOOP; 6 COMMIT; 7 END; 8 / PL/SQL procedure successfully completed. ...
SQL> begin 2 for I in 1 .. 10000 loop 3 insert into DAVE values(I); 4 end loop; 5 commit; 6 end; 7 / PL/SQL procedure successfully completed. SQL> create index idx_id on dave(id)invisible; Index created. SQL> execdbms_stats.gather_table_stats(ownname =>'&owner',tabname=>'...
SQL> create table colocated ( x int, y varchar2(80) ); 表已创建。 1begin 2for i in 1 .. 100000 3loop 4insert into colocated(x,y) 5values (i, rpad(dbms_random.random,75,'*') ); 6end loop; 7*end; 8/ PL/SQL过程已成功完成。
user_indexes join user_ind_columns ic using (table_name,index_name) : user_ind_columns « System Tables Views « Oracle PL / SQL