OracleSQL精妙SQL语句讲解

2012-11-12

  --行列转换 行转列

  DROP TABLE t_change_lc;

  CREATE TABLE t_change_lc (card_code VARCHAR2(3), q NUMBER, bal NUMBER);

  INSERT INTO t_change_lc

  SELECT '001' card_code, ROWNUM q, trunc(dbms_random.VALUE * 100) bal FROM dual CONNECT BY ROWNUM <= 4

  UNION

  SELECT '002' card_code, ROWNUM q, trunc(dbms_random.VALUE * 100) bal FROM dual CONNECT BY ROWNUM <= 4;

  SELECT * FROM t_change_lc;

  SELECT a.card_code,

  SUM(decode(a.q, 1, a.bal, 0)) q1,

  SUM(decode(a.q, 2, a.bal, 0)) q2,

  SUM(decode(a.q, 3, a.bal, 0)) q3,

  SUM(decode(a.q, 4, a.bal, 0)) q4

  FROM t_change_lc a

  GROUP BY a.card_code

  ORDER BY 1;

  --行列转换 列转行

  DROP TABLE t_change_cl;

  CREATE TABLE t_change_cl AS

  SELECT a.card_code,

  SUM(decode(a.q, 1, a.bal, 0)) q1,

  SUM(decode(a.q, 2, a.bal, 0)) q2,

  SUM(decode(a.q, 3, a.bal, 0)) q3,

  SUM(decode(a.q, 4, a.bal, 0)) q4

  FROM t_change_lc a

  GROUP BY a.card_code

  ORDER BY 1;

  SELECT * FROM t_change_cl;

  SELECT t.card_code,

  t.rn q,

  decode(t.rn, 1, t.q1, 2, t.q2, 3, t.q3, 4, t.q4) bal

  FROM (SELECT a.*, b.rn

  FROM t_change_cl a,

  (SELECT ROWNUM rn FROM dual CONNECT BY ROWNUM <= 4) b) t

  ORDER BY 1, 2;

  --行列转换 行转列 合并

  DROP TABLE t_change_lc_comma;

  CREATE TABLE t_change_lc_comma AS SELECT card_code,'quarter_'||q AS q FROM t_change_lc;

  SELECT * FROM t_change_lc_comma;

  SELECT t1.card_code, substr(MAX(sys_connect_by_path(t1.q, ';')), 2) q

  FROM (SELECT a.card_code,

  a.q,

  row_number() over(PARTITION BY a.card_code ORDER BY a.q) rn

  FROM t_change_lc_comma a) t1

  START WITH t1.rn = 1

  CONNECT BY t1.card_code = PRIOR t1.card_code

  AND t1.rn - 1 = PRIOR t1.rn

  GROUP BY t1.card_code;

  --行列转换 列转行 分割

  DROP TABLE t_change_cl_comma;

  CREATE TABLE t_change_cl_comma AS

  SELECT t1.card_code, substr(MAX(sys_connect_by_path(t1.q, ';')), 2) q

  FROM (SELECT a.card_code,

  a.q,

  row_number() over(PARTITION BY a.card_code ORDER BY a.q) rn

  FROM t_change_lc_comma a) t1

  START WITH t1.rn = 1

  CONNECT BY t1.card_code = PRIOR t1.card_code

  AND t1.rn - 1 = PRIOR t1.rn

  GROUP BY t1.card_code;

  SELECT * FROM t_change_cl_comma;

  SELECT t.card_code,

  substr(t.q,

  instr(';' || t.q, ';', 1, rn),

  instr(t.q || ';', ';', 1, rn) - instr(';' || t.q, ';', 1, rn)) q

  FROM (SELECT a.card_code, a.q, b.rn

  FROM t_change_cl_comma a,

  (SELECT ROWNUM rn FROM dual CONNECT BY ROWNUM <= 100) b

  WHERE instr(';' || a.q, ';', 1, rn) > 0) t

  ORDER BY 1, 2;

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