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select * from (select st_base_id from t_base order by dbms_random.random) where rownum<=100; --Õâ¸öÊÇËæ»úÈ¡³ö100¸ö¼Ç¼¡£
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select dbms_random.string('u',100) from dual; --²úÉú´óд×Öĸ×é³ÉµÄ×Ö·û´®£¬'u'Ò²¿ÉÒÔд³É'U'
select dbms_random.string('l',100) from dual; --²úÉúСд×Öĸ×é³ÉµÄ×Ö·û´®£¬'l'Ò²¿ÉÒÔд³É'L'
select dbms_random.string('a',100) from dual; --²úÉú´óСд×Öĸ»ìºÏ×é³ÉµÄ×Ö·û´®£¬'a'Ò²¿ÉÒÔд³É'A'
select dbms_random.string('x',100) from dual; --²úÉú´óд×ÖĸºÍÊý×Ö»ìºÏ×é³ÉµÄ×Ö·û´®£¬'x'Ò²¿ÉÒÔд³É'X'
select dbms_random.string('p',100) from dual; --²úÉúÈκοɴòÓ¡³öÀ´µÄ×Ö·û×é³ÉµÄ×Ö·û´®£¬'p'Ò²¿ÉÒÔд³É'P'
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select dbms_random.random from dual; --²úÉúÈÎÒâ´óСµÄËæ»úÕûÊý£¬·µ»ØÖµ·¶Î§Çø¼äÊÇ[-2^31,2^31)
select abs(mod(dbms_random.random,100)) from dual; --²úÉú·¶Î§Çø¼äΪ[0,100)µÄËæ»úÕûÊý
select abs(mod(dbms_random.random,1000)) from dual; --²úÉú·¶Î§Çø¼äΪ[0,1000)µÄËæ»úÕûÊý
select trunc(dbms_random.value(100,1000)) from dual; --²úÉú·¶Î§Çø¼äΪ[100,1000)µÄËæ»úÕûÊý
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select dbms_random.normal from dual; --°´±ê×¼Õý̬·Ö²¼²úÉúËæ»úÊý£¬¸ÃÕý̬·Ö²¼±ê׼ƫ²îΪ1£¬ÆÚÍûֵΪ0¡£Õâ¸öº¯Êý·µ»ØµÄÊýÖµÖÐÓÐ68%ÊǽéÓÚ-1Óë+1Ö®¼ä£¬95%½éÓÚ-2Óë+2Ö®¼ä£¬99%½éÓÚ-3Óë+3Ö®¼ä¡£
select dbms_random.value from dual; --²úÉú·¶Î§Çø¼äΪ[0,1)µÄËæ»úÊý£¬ÓÐЧÊý×ÖΪ38λ
select dbms_random.value(100,1000) from dual; --²úÉú·¶Î§Çø¼äΪ[100,1000)µÄËæ»úÊý
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1. select * from emp;
2. select empno, ename, job from emp;
3. select empno ±àºÅ, ename ÐÕÃû, job ¹¤×÷ from emp;
4. select job from emp;
5. select distinct job from emp;
6. select distinct empno, job from emp;
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* start Oracle *
set noexec_user_stack=1
set msgsys:msginfo_msgmax=65535
set msgsys:msginfo_msgmnb=65535
set msgsys:msginfo_msgmap=258
set msgsys:msginfo_msgmni=1792
set msgsys:msginfo_msgssz=32
set msgsys:msginfo_msgtql=1792
set msgsys:msginfo_msgseg=32767
set shmsys:shminfo_shmmax=4294967 ......
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1.creating function-based indexes
sql> create index summit.item_quantity on summit.item(quantity-quantity_shipped);
2.create a B-tree index
sql> create [unique] index index_name on table_name(column,.. asc/desc) tablespace
sql> tablespace_name [pctfree integer] ......