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SQL ÄÄÆÄÀÏ·¯´Â ±âÁ¸ÀÇ Á¶È¸¸¦ ƯÁ¤ Á¶È¸¿¡ ´ëÇØ º¸´Ù ÃÖÀûÈ­µÈ ¼ú¾î·Î º¯È¯Çϵµ·Ï Á¶È¸¸¦ ÀçÀÛ¼ºÇÕ´Ï´Ù. ´ÙÀ½ ¿¹´Â SQL ÄÄÆÄÀÏ·¯·Î º¯È¯µÉ ¼ö ÀÖ´Â ÀϺΠ¼ú¾î¸¦ ¼³¸íÇϱâ À§ÇØ Á¦°øµË´Ï´Ù.

¿¹ - ¾Ï½ÃÀû ¼ú¾îÀÇ Ãß°¡

´ÙÀ½ Á¶È¸´Â "E01"¿¡°Ô º¸°íÇÏ´Â ºÎ¼­ÀÇ °ü¸®ÀÚµé°ú ÇØ´ç °ü¸®ÀÚ°¡ ´ã´çÇÏ´Â ÇÁ·ÎÁ§Æ®ÀÇ ¸ñ·ÏÀ» ÀÛ¼ºÇÕ´Ï´Ù.

   SELECT DEPT.DEPTNAME DEPT.MGRNO, EMP.LASTNAME, PROJ.PROJNAME
     FROM DEPARTMENT DEPT,
          EMPLOYEE   EMP,
          PROJECT    PROJ
    WHERE DEPT.ADMRDEPT = 'E01'
      AND DEPT.MGRNO = EMP.EMPNO
      AND EMP.EMPNO  = PROJ.RESPEMP

Á¶È¸¸¦ ÀçÀÛ¼ºÇϸé, ´ÙÀ½ ¾Ï½ÃÀû ¼ú¾î¸¦ Ãß°¡ÇÕ´Ï´Ù.

   DEPT.MGRNO = PROJ.RESPEMP

ÀÌ ÀçÀÛ¼ºÀÇ °á°ú, ÃÖÀûÈ­ ¾Ë°í¸®ÁòÀº ÇØ´ç Á¶È¸¿¡ ´ëÇÑ ÃÖ»óÀÇ ¾×¼¼½º Ç÷£À» ¼±ÅÃÇÏ·Á°í ½ÃµµÇÒ ¶§ Ãß°¡ Á¶ÀÎÀ» °í·ÁÇÒ ¼ö ÀÖ½À´Ï´Ù.

À§ÀÇ ¼ú¾î ÀüÀÌ Æó¼â À̿ܿ¡, Á¶È¸¸¦ ÀçÀÛ¼ºÇÏ¸é µ¿µî ¼ú¾î¿¡ ÀÇÇØ ¾Ï½ÃµÇ´Â ÀüÀ̼º¿¡ ±âÃÊÇÏ¿© Ãß°¡ Áö¿ª ¼ú¾îµµ À¯µµÇÕ´Ï´Ù. ¿¹¸¦ µé¸é, ´ÙÀ½ÀÇ Á¶È¸´Â ºÎ¼­(ºÎ¼­ ¹øÈ£°¡ "E00"º¸´Ù Å« ºÎ¼­)¿Í ÇØ´ç ºÎ¼­¿¡¼­ ÀÏÇÏ´Â Á÷¿øÀÇ À̸§À» ³ª¿­ÇÕ´Ï´Ù.

   SELECT EMPNO, LASTNAME, FIRSTNAME, DEPTNO, DEPTNAME
     FROM EMPLOYEE EMP,
          DEPARTMENT DEPT
    WHERE EMP.WORKDEPT = DEPT.DEPTNO
      AND DEPT.DEPTNO > 'E00'

ÀÌ Á¶È¸ÀÇ °æ¿ì, ÀçÀÛ¼º ´Ü°è´Â ´ÙÀ½ÀÇ ¾Ï½ÃÀû ¼ú¾î¸¦ Ãß°¡ÇÕ´Ï´Ù.

   EMP.WORKDEPT > 'E00'

ÀÌ ÀçÀÛ¼ºÀÇ °á°ú·Î ÃÖÀûÈ­ ¾Ë°í¸®ÁòÀº Á¶ÀεǴ ÇàÀÇ ¼ö¸¦ ÁÙÀÔ´Ï´Ù.

¿¹ - OR¿¡¼­ INÀ¸·ÎÀÇ º¯È¯

´ÙÀ½ÀÇ ¿¹¿¡¼­Ã³·³, µ¿ÀÏÇÑ Ä÷³¿¡ ´ëÇÑ µÑ ÀÌ»óÀÇ µ¿µî ¼ú¾î¸¦ ¿¬°áÇÏ´Â ORÀýÀÌ ÀÖ´Ù°í °¡Á¤ÇϽʽÿÀ.

     SELECT *
     FROM EMPLOYEE
    WHERE DEPTNO = 'D11'
       OR DEPTNO = 'D21'
       OR DEPTNO = 'E21'

DEPTNO Ä÷³¿¡ ´ëÇÑ »öÀÎÀÌ ¾ø´Â °æ¿ì, ORÀýÀ» ´ÙÀ½ÀÇ IN ¼ú¾î·Î º¯È¯Çϸé Á¶È¸¸¦ º¸´Ù È¿À²ÀûÀ¸·Î ó¸®ÇÒ ¼ö ÀÖ½À´Ï´Ù.

     SELECT *
     FROM EMPLOYEE
    WHERE DEPTNO IN ('D11', 'D21', 'E21')
ÁÖ:ÀϺΠ°æ¿ì¿¡´Â, »öÀÎ OR ÀÛ¾÷À» ¼öÇàÇÒ ¼ö ÀÖµµ·Ï µ¥ÀÌÅͺ£À̽º °ü¸® ÇÁ·Î±×·¥ÀÌ IN ¼ú¾î¸¦ ORÀýÀÇ ÁýÇÕÀ¸·Î º¯È¯Çϱ⵵ ÇÕ´Ï´Ù. »öÀÎ OR ÀÛ¾÷¿¡ ´ëÇØ¼­´Â ´ÙÁß »öÀÎ ¾×¼¼½º¿¡¼­ ÀÚ¼¼ÇÑ ³»¿ëÀ» ÂüÁ¶ÇϽʽÿÀ.


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