oracle语句优化30例子

SQLÓï¾äÓÅ»¯·½·¨30ÀýÔÚSQLÓï¾äÓÅ»¯¹ý³ÌÖУ­ÎÒÃǾ�³£»áÓõ½hint,ÏÖ×ܽáÒ»ÏÂÔÚSQLÓÅ»¯¹ý³ÌÖг£¼ûOracle HINTµÄÓ÷¨£º1. /*+ALL_ROWS*/ ±íÃ÷��Óï¾ä¿éÑ¡Ôñ»ùÓÚ¿ªÏúµÄÓÅ»¯·½·¨,²¢»ñµÃ×î¼ÑÍÌÍÂÁ¿,ʹ×ÊÔ´ÏûºÄ×îС»¯. ÀýÈç: SELECT /*+ALL+_ROWS*/ EMP_NO,EMP_NAM,DAT_IN FROM BSEMPMS WHERE EMP_NO='SCOTT'; 2. /*+FIRST_ROWS*/ ±íÃ÷��Óï¾ä¿éÑ¡Ôñ»ùÓÚ¿ªÏúµÄÓÅ»¯·½·¨,²¢»ñµÃ×î¼ÑÏìӦʱ¼ä,ʹ×ÊÔ´ÏûºÄ×îС»¯. ÀýÈç: SELECT /*+FIRST_ROWS*/ EMP_NO,EMP_NAM,DAT_IN FROM BSEMPMS WHERE EMP_NO='SCOTT'; 3. /*+CHOOSE*/ ±íÃ÷Èç¹ûÊý¾Ý×ÖµäÖÐÓзÃÎʱíµÄͳ¼ÆÐÅÏ¢,½«»ùÓÚ¿ªÏúµÄÓÅ»¯·½·¨,²¢»ñµÃ×î¼ÑµÄÍÌÍÂÁ¿; ±íÃ÷Èç¹ûÊý¾Ý×ÖµäÖÐûÓзÃÎʱíµÄͳ¼ÆÐÅÏ¢,½«»ùÓÚ¹æÔò¿ªÏúµÄÓÅ»¯·½·¨; ÀýÈç: SELECT /*+CHOOSE*/ EMP_NO,EMP_NAM,DAT_IN FROM BSEMPMS WHERE EMP_NO='SCOTT'; 4. /*+RULE*/ ±íÃ÷��Óï¾ä¿éÑ¡Ôñ»ùÓÚ¹æÔòµÄÓÅ»¯·½·¨. ÀýÈç: SELECT /*+ RULE */ EMP_NO,EMP_NAM,DAT_IN FROM BSEMPMS WHERE EMP_NO='SCOTT'; 5. /*+FULL(TABLE)*/ ±íÃ÷��±íÑ¡ÔñÈ«¾ÖɨÃèµÄ·½·¨. ÀýÈç: SELECT /*+FULL(A)*/ EMP_NO,EMP_NAM FROM BSEMPMS A WHERE EMP_NO='SCOTT'; 6. /*+ROWID(TABLE)*/ ÌáʾÃ÷È·±íÃ÷��Ö¸��±í¸ù¾ÝROWID½øÐзÃÎÊ. ÀýÈç: SELECT /*+ROWID(BSEMPMS)*/ * FROM BSEMPMS WHERE ROWID>='AAAAAAAAAAAAAA' AND EMP_NO='SCOTT'; 7. /*+CLUSTER(TABLE)*/ ÌáʾÃ÷È·±íÃ÷��Ö¸��±íÑ¡Ôñ´ØɨÃèµÄ·ÃÎÊ·½·¨,ËüÖ»��´Ø��ÏóÓÐЧ. ÀýÈç: SELECT /*+CLUSTER */ BSEMPMS.EMP_NO,DPT_NO FROM BSEMPMS,BSDPTMS WHERE DPT_NO='TEC304' AND BSEMPMS.DPT_NO=BSDPTMS.DPT_NO; 8. /*+INDEX(TABLE INDEX_NAME)*/ ±íÃ÷��±íÑ¡ÔñË÷ÒýµÄɨÃè·½·¨. ÀýÈç: SELECT /*+INDEX(BSEMPMS SEX_INDEX) USE SEX_INDEX BECAUSE THERE ARE FEWMALE BSEMPMS */ FROM BSEMPMS WHERE SEX='M'; 9. /*+INDEX_ASC(TABLE INDEX_NAME)*/ ±íÃ÷��±íÑ¡ÔñË÷ÒýÉýÐòµÄɨÃè·½·¨. ÀýÈç: SELECT /*+INDEX_ASC(BSEMPMS PK_BSEMPMS) */ FROM BSEMPMS WHERE DPT_NO='SCOTT'; 10. /*+INDEX_COMBINE*/ Ϊָ��±íÑ¡Ôñλͼ·ÃÎÊ·¾�,Èç¹ûINDEX_COMBINEÖÐûÓÐÌṩ×÷Ϊ²ÎÊýµÄË÷Òý,½«Ñ¡Ôñ³öλͼË÷ÒýµÄ²¼��×éºÏ·½Ê½. ÀýÈç: SELECT /*+INDEX_COMBINE(BSEMPMS SAL_BMI HIREDATE_BMI)*/ * FROM BSEMPMS WHERE SAL<5000000 AND HIREDATE<SYSDATE; 11. /*+INDEX_JOIN(TABLE INDEX_NAME)*/ ÌáʾÃ÷È·ÃüÁîÓÅ»¯Æ÷ʹÓÃË÷Òý×÷Ϊ·ÃÎÊ·¾�. ÀýÈç: SELECT /*+INDEX_JOIN(BSEMPMS SAL_HMI HIREDATE_BMI)*/ SAL,HIREDATE FROM BSEMPMS WHERE SAL<60000; 12. /*+INDEX_DESC(TABLE INDEX_NAME)*/ ±íÃ÷��±íÑ¡ÔñË÷Òý½µÐòµÄɨÃè·½·¨. ÀýÈç: SELECT /*+INDEX_DESC(BSEMPMS PK_BSEMPMS) */ FROM BSEMPMS WHERE DPT_NO='SCOTT'; 13. /*+INDEX_FFS(TABLE INDEX_NAME)*/ ��Ö¸��µÄ±íÖ´ÐпìËÙÈ«Ë÷ÒýɨÃè,��²»ÊÇÈ«±íɨÃèµÄ°ì·¨. ÀýÈç: SELECT /*+INDEX_FFS(BSEMPMS IN_EMPNAM)*/ * FROM BSEMPMS WHERE DPT_NO='TEC305'; 14. /*+ADD_EQUAL TABLE INDEX_NAM1,INDEX_NAM2,...*/ ÌáʾÃ÷È·½øÐÐÖ´Ðй滮µÄÑ¡Ôñ,½«¼¸¸öµ¥ÁÐË÷ÒýµÄɨÃèºÏÆðÀ´. ÀýÈç: SELECT /*+INDEX_FFS(BSEMPMS IN_DPTNO,IN_EMPNO,IN_SEX)*/ * FROM BSEMPMS WHERE EMP_NO='SCOTT' AND DPT_NO='TDC306'; 15. /*+USE_CONCAT*/ ��²éѯÖеÄWHEREºóÃæµÄORÌõ¼þ½øÐÐת»»ÎªUNION ALLµÄ×éºÏ²éѯ. ÀýÈç: SELECT /*+USE_CONCAT*/ * FROM BSEMPMS WHERE DPT_NO='TDC506' AND SEX='M'; 16. /*+NO_EXPAND*/ ��ÓÚWHEREºóÃæµÄOR »òÕßIN-LISTµÄ²éѯÓï¾ä,NO_EXPAND½«×èÖ¹Æä»ùÓÚÓÅ»¯Æ÷��Æä½øÐÐÀ©Õ¹. ÀýÈç: SELECT /*+NO_EXPAND*/ * FROM BSEMPMS WHERE DPT_NO='TDC506' AND SEX='M'; 17. /*+NOWRITE*/ ½ûÖ¹��²éѯ¿éµÄ²éѯÖØд²Ù×÷. 18. /*+REWRITE*/ ¿ÉÒÔ½«ÊÓͼ×÷Ϊ²ÎÊý. 19. /*+MERGE(TABLE)*/ Äܹ»��ÊÓͼµÄ¸÷¸ö²éѯ½øÐÐÏàÓ¦µÄºÏ²¢. ÀýÈç: SELECT /*+MERGE(V) */ A.EMP_NO,A.EMP_NAM,B.DPT_NO FROM BSEMPMS A (SELET DPT_NO ,AVG(SAL) AS AVG_SAL FROM BSEMPMS B GROUP BY DPT_NO) V WHERE A.DPT_NO=V.DPT_NO AND A.SAL>V.AVG_SAL; 20. /*+NO_MERGE(TABLE)*/ ��ÓÚÓпɺϲ¢µÄÊÓͼ²»Ôٺϲ¢. ÀýÈç: SELECT /*+NO_MERGE(V) */ A.EMP_NO,A.EMP_NAM,B.DPT_NO FROM BSEMPMS A (SELECT DPT_NO,AVG(SAL) AS AVG_SAL FROM BSEMPMS B GROUP BY DPT_NO) V WHERE A.DPT_NO=V.DPT_NO AND A.SAL>V.AVG_SAL; 21. /*+ORDERED*/ ¸ù¾Ý±í³öÏÖÔÚFROMÖеÄ˳Ðò,ORDEREDʹORACLEÒÀ´Ë˳Ðò��ÆäÁ­½Ó. ÀýÈç: SELECT /*+ORDERED*/ A.COL1,B.COL2,C.COL3 FROM TABLE1 A,TABLE2 B,TABLE3 C WHERE A.COL1=B.COL1 AND B.COL1=C.COL1; 22. /*+USE_NL(TABLE)*/ ½«Ö¸��±íÓëÇ�Ì×µÄÁ­½ÓµÄÐÐÔ´½øÐÐÁ­½Ó,²¢°ÑÖ¸��±í×÷ΪÄÚ²¿±í. ÀýÈç: SELECT /*+ORDERED USE_NL(BSEMPMS)*/ BSDPTMS.DPT_NO,BSEMPMS.EMP_NO,BSEMPMS.EMP_NAM FROM BSEMPMS,BSDPTMS WHERE BSEMPMS.DPT_NO=BSDPTMS.DPT_NO; 23. /*+USE_MERGE(TABLE)*/ ½«Ö¸��µÄ±íÓëÆäËûÐÐԴͨ¹ýºÏ²¢ÅÅÐòÁ­½Ó·½Ê½Á­½ÓÆðÀ´. ÀýÈç: SELECT /*+USE_MERGE(BSEMPMS,BSDPTMS)*/ * FROM BSEMPMS,BSDPTMS WHERE BSEMPMS.DPT_NO=BSDPTMS.DPT_NO; 24. /*+USE_HASH(TABLE)*/ ½«Ö¸��µÄ±íÓëÆäËûÐÐԴͨ¹ý¹þÏ£Á­½Ó·½Ê½Á­½ÓÆðÀ´. ÀýÈç: SELECT /*+USE_HASH(BSEMPMS,BSDPTMS)*/ * FROM BSEMPMS,BSDPTMS WHERE BSEMPMS.DPT_NO=BSDPTMS.DPT_NO; 25. /*+DRIVING_SITE(TABLE)*/ Ç¿ÖÆÓëORACLEËùÑ¡ÔñµÄλÖò»Í­µÄ±í½øÐвéѯִÐÐ. ÀýÈç: SELECT /*+DRIVING_SITE(DEPT)*/ * FROM BSEMPMS,DEPT@BSDPTMS WHERE BSEMPMS.DPT_NO=DEPT.DPT_NO; 26. /*+LEADING(TABLE)*/ ½«Ö¸��µÄ±í×÷ΪÁ­½Ó´ÎÐòÖеÄÊ×±í. 27. /*+CACHE(TABLE)*/ µ±½øÐÐÈ«±íɨÃèʱ,CACHEÌáʾÄܹ»½«±íµÄ¼ìË÷¿é·ÅÖÃÔÚ»º³åÇø»º´æÖÐ×î½ü×îÉÙÁбíLRUµÄ×î½üʹÓÃ�� ÀýÈç: SELECT /*+FULL(BSEMPMS) CAHE(BSEMPMS) */ EMP_NAM FROM BSEMPMS; 28. /*+NOCACHE(TABLE)*/ µ±½øÐÐÈ«±íɨÃèʱ,CACHEÌáʾÄܹ»½«±íµÄ¼ìË÷¿é·ÅÖÃÔÚ»º³åÇø»º´æÖÐ×î½ü×îÉÙÁбíLRUµÄ×î½üʹÓÃ�� ÀýÈç: SELECT /*+FULL(BSEMPMS) NOCAHE(BSEMPMS) */ EMP_NAM FROM BSEMPMS; 29. /*+APPEND*/ Ö±½Ó²åÈëµ½±íµÄ×îºó,¿ÉÒÔÌá¸ßËÙ��. insert /*+append*/ into test1 select * from test4 ; 30. /*+NOAPPEND*/ ͨ¹ýÔÚ²åÈëÓï¾äÉú´æÆÚÄÚÍ£Ö¹²¢ÐÐģʽÀ´Æô��³£¹æ²åÈë. insert /*+noappend*/ into test1 select * from test4 ;