Oracle查询将行划分为分隔符

Question

我有如下数据。

Attribute	operator	value
col1	=	02
col2	In	('001','002')
col3	<>	A
col4	Not In	('test1','test2','test3')

我正在尝试将其转换为以下格式。

col1=02 AND col2=001 OR col2=002 AND col3<>A AND col4<>test1 AND col4<>test2 AND col4<>test3

您能否建议 oracle SELECT 查询。

提前致谢。

Answer 1

如果您想检查 Oracle 如何解释谓词，只需使用包含您的谓词的 WHEREclause 创建查询。

具有对应列的表必须存在但可能为空。

然后调用explain plan 并查看结果 - 检查谓词信息中的filter

EXPLAIN PLAN  SET STATEMENT_ID = 'jara1' into   plan_table  FOR
select * from tab
where 
col1 = 02 and
col2 in ('001','002') and
col3 <> 'A' and
col4 not in ('test1','test2','test3');

得到结果（为简洁起见）

SELECT * FROM table(DBMS_XPLAN.DISPLAY('plan_table', 'jara1','ALL'));

...
Predicate Information (identified by operation id):
---------------------------------------------------
 
   1 - filter("COL1"=02 AND ("COL2"='001' OR "COL2"='002') AND 
              "COL3"<>'A' AND "COL4"<>'test1' AND "COL4"<>'test2' AND "COL4"<>'test3')

Answer 2

你可以写一个函数：

CREATE FUNCTION parse_filters
RETURN CLOB
IS
  v_sql  CLOB := EMPTY_CLOB();
  v_expr CLOB;
  c_in_value_pattern VARCHAR2(60)
    := '('
       || '\d+\.\d*|\.\d+'    -- Number literal
       || '|'
       || '''([^'']|'''')*''' -- String literal
       || '|'
       || '".*?"'             -- Quoted identifier
       || '|'
       || '[A-Z][A-Z0-9_$#]*' -- Identifier
       || '),?';

  PROCEDURE append_expr(
    p_sql           IN OUT CLOB,
    p_expr          IN     CLOB,
    p_oper          IN     VARCHAR2,
    p_wrap          IN     BOOLEAN DEFAULT FALSE
  )
  IS
    v_is_start CONSTANT BOOLEAN := LENGTH(p_sql) = 0;
  BEGIN
    IF NOT v_is_start THEN
      p_sql := p_sql || ' ';
    END IF;
    IF NOT v_is_start THEN
      p_sql := p_sql || p_oper || ' ';
    END IF;
    IF p_wrap THEN
      p_sql := p_sql || '(' || p_expr || ')';
    ELSE
      p_sql := p_sql || p_expr;
    END IF;
  END;
BEGIN
  FOR f IN (SELECT attribute, operator, value FROM filters)
  LOOP
    IF f.operator IN ('=', '<>', '!=') THEN
      v_expr := EMPTY_CLOB() || f.attribute || ' ' || f.operator || ' ' || f.value;
      append_expr(v_sql, v_expr, 'AND');
    ELSIF LOWER(f.operator) = 'in' THEN
      DECLARE
        v_list FILTERS.VALUE%TYPE := SUBSTR(f.value, 2, LENGTH(f.value) - 2);
        v_term FILTERS.VALUE%TYPE;
        v_idx  PLS_INTEGER := 1;
        v_temp CLOB;
      BEGIN
        v_expr := EMPTY_CLOB();
        LOOP
          v_term := REGEXP_SUBSTR(f.value, c_in_value_pattern, 1, v_idx, 'i', 1);
          EXIT WHEN v_term IS NULL;
          v_temp := EMPTY_CLOB() || f.attribute || ' = ' || v_term;
          append_expr(v_expr, v_temp, 'OR');
          v_idx := v_idx + 1;
        END LOOP;
        append_expr(v_sql, v_expr, 'AND', TRUE);
      END;
    ELSIF LOWER(f.operator) = 'not in' THEN
      DECLARE
        v_list FILTERS.VALUE%TYPE := SUBSTR(f.value, 2, LENGTH(f.value) - 2);
        v_term FILTERS.VALUE%TYPE;
        v_idx  PLS_INTEGER := 1;
      BEGIN
        LOOP
          v_term := REGEXP_SUBSTR(f.value, c_in_value_pattern, 1, v_idx, 'i', 1);
          EXIT WHEN v_term IS NULL;
          v_expr := EMPTY_CLOB() || f.attribute || ' <> ' || v_term;
          append_expr(v_sql, v_expr, 'AND');
          v_idx := v_idx + 1;
        END LOOP;
      END;
    END IF;
  END LOOP;
  RETURN v_sql;
END parse_filters;
/

对于您的示例数据：

CREATE TABLE filters ( Attribute, operator, value ) AS
SELECT 'col1', '=',      '''02''' FROM DUAL UNION ALL
SELECT 'col2', 'In',     '(''001'',''002'')' FROM DUAL UNION ALL
SELECT 'col3', '<>',     '''A''' FROM DUAL UNION ALL
SELECT 'col4', 'Not In', '(''test1'',''test2'',''test3'')' FROM DUAL;

然后：

SELECT parse_filters() FROM DUAL;

输出：

PARSE_FILTERS()
col1 = '02' AND (col2 = '001' OR col2 = '002') AND col3 <> 'A' AND col4 <> 'test1' AND col4 <> 'test2' AND col4 <> 'test3'

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