■예 4_2_1  ||  기본 ____SELECT 쿼리
SELECT   T2.ACAD_ABILITY, AVG(T1.AGE) AS AVG_AGE
FROM   CHAPTER_1  T1, CHAPTER_2  T2
WHERE  T1.SABUN  =  T2.SABUN
GROUP BY  T2.ACAD_ABILITY
HAVING   T2.ACAD_ABILITY='대졸';

■예 4_2_2  || 기본 SELECT 쿼리
SELECT T1.SABUN AS SABUN,  T1.NAME AS NAME,  T1.AGE,
 T2.ACAD_ABILITY,  T2.MAJOR_STUDY,  T2.GRAT_YM
FROM      CHAPTER_1 T1,  CHAPTER_2 T2
WHERE T1.SABUN = T2.SABUN
AND T2.ACAD_ABILITY = '대졸'
ORDER BY  AGE  DESC;

■예 4_2_3  ||  기본 SELECT 쿼리
SELECT   T2.ACAD_ABILITY,   NVL(T2.MAJOR_STUDY, ' - '),   COUNT(*)  TOTAL_COUNT
FROM    CHAPTER_1  T1,   CHAPTER_2  T2
WHERE   T1.SABUN = T2.SABUN
GROUP BY ROLLUP(T2.ACAD_ABILITY,   T2.MAJOR_STUDY)
HAVING   T2.ACAD_ABILITY = '대졸';

■예 4_2_4  ||  기본 SELECT 쿼리
--SQL1
SELECT AVG(AGE) AVG_AGE
FROM TALBLE_1;

--SQL2
SELECT SABUN,  NAME,  AGE  
FROM TABLE_1
WHERE AGE <= '27';

■예 4_2_5  ||  SUBQUERY를 활용한 데이터 조회
SELECT  SABUN,  NAME,  AGE
FROM   CHAPTER_1
WHERE  AGE <= ( SELECT  AVG(AGE) AS AVG_AGE
                       FROM   CHAPTER_1 );

■예 4_2_6  ||  SELECT문
SELECT
        DECODE(T2.RECT_REG_NO,NULL,'합계',T2.RECT_REG_NO) AS 채용등록번호,
        DECODE( T2.RECT_REG_NO,NULL,'',MAX(T2.PJT_NAME)) AS 프로잭트명,
        DECODE( T2.RECT_REG_NO,NULL,'',MAX(T2.PJT_PLACE)) AS 프로잭트장소,
 DECODE( T2.RECT_REG_NO,NULL,'',MAX(DECODE(T2.PUT_START_DAY,NULL,'0001/01/01',TO_CHAR(T2.PUT_START_DAY,'YYYY/MM/DD')))) AS 투입시작일,
 DECODE( T2.RECT_REG_NO,NULL,'',MAX(DECODE(T2.PUT_END_DAY,NULL,'9999/12/31',TO_CHAR(T2.PUT_END_DAY,'YYYY/MM/DD')))) AS  투입종료일자,
        DECODE( T2.RECT_REG_NO,NULL,'총'||COUNT(T1.SABUN)||'명',MAX(T1.NAME)||(DECODE(COUNT(T1.SABUN),0,'0명',DECODE(COUNT(T1.SABUN),1,'','외'||(COUNT(T1.SABUN)-1)||'명')))) AS 투입인원수      
FROM   INSA T1,--인사마스터
        ( SELECT
                TT1.RECT_REG_NO
  ,TT1.PJT_NAME
  ,TT1.PJT_PLACE
  ,TT1.PUT_START_DAY
                ,TT1.PUT_END_DAY
  ,TT2.SABUN
          FROM  INSA_RECT_NOTICE TT1, --채용공고
                INSA_EMP_PJT TT2 --사원별프로젝트
          WHERE TT1.RECT_REG_NO = TT2.RECT_REG_NO(+)
   AND   TT1.PJT_NAME LIKE :IN_PJT_NAME||'%'  --프로젝트명을 받는다.
        ) T2
WHERE T2.SABUN = T1.SABUN(+)
GROUP BY ROLLUP(T2.RECT_REG_NO)
ORDER BY T2.RECT_REG_NO;

■예 4_2_7  ||  SELECT문    
SELECT T1.CMP_NAME AS 업체명, T2.NAME AS 성명,
 (SELECT CODE_NAME  FROM CMM_CODE_DETAIL TT2  WHERE T2.POS_GBN_CODE = TT2.CODE_NO AND TT2.CLASS_CODE = 'C03' --직위구문코드) AS 직위명,
 (SELECT CODE_NAME FROM____ CMM_CODE_DETAIL TT2   WHERE T2.CLASS_GBN_CODE = TT2.CODE_NO AND TT2.CLASS_CODE = 'B01' --등급구분코드) AS 등급명,
 T4.PJT_NAME AS 프로젝트명,
 T3.PUT_START_DAY AS 투입시작일자,
 T3.PUT_END_DAY AS 투입종료일자,
 T1.SALE_COMPT_NAME AS 영업담당자,
 T1.CMP_PHONE AS 업체전화번호
FROM INSA_COMPANY T1, --업체
 INSA T2,         --인사마스터
 INSA_EMP_PJT T3, --사원별프로젝트
 INSA_RECT_NOTICE T4 --채용공고
WHERE  1=1
       AND T1.CMP_REG_NO = T2.CMP_REG_NO
       AND T2.SABUN = T3.SABUN
       AND T3.RECT_REG_NO = T4.RECT_REG_NO
       AND (
     (T3.PUT_START_DAY>=TO_DATE(:IN_F_PUT_START_DAY,'YYYYMMDD') AND T3.PUT_START_DAY <TO_DATE(:IN_T_PUT_START_DAY,'YYYYMMDD')+1)
             OR
            (T3.PUT_END_DAY>=TO_DATE(:IN_F_PUT_START_DAY,'YYYYMMDD') AND T3.PUT_END_DAY <TO_DATE(:IN_T_PUT_START_DAY,'YYYYMMDD')+1)
    )
       AND T1.CMP_NAME LIKE :IN_CMP_NAME||'%';