GBase 8s数据库的boolean类型取值为：'t','f',null。其它数据库可接受对应的1,0,null的数值写法。为了兼容使用，可临时自定义转换及等值及不等值操作函数的方式实现兼容。

以下为自定义转换，及等值（equal)及不等值（notequal)函数写法示例：

SET environment sqlmode 'gbase';
DROP FUNCTION IF EXISTS int2boolean(int);
-- 允许接受空值
CREATE FUNCTION int2boolean(p1 int)
RETURNS boolean WITH (NOT variant);
  IF p1 = 0 THEN 
    RETURN 'f';
  ELIF p1 IS NULL THEN 
    RETURN NULL;
  END IF;
  RETURN 't';
END FUNCTION;

DROP CAST IF EXISTS(int as boolean);
-- 创建转换：int转换为boolean，使用int2boolean函数；
CREATE implicit CAST IF NOT EXISTS (int AS boolean WITH int2boolean);

DROP FUNCTION IF EXISTS equal(boolean,int);
-- 两个参数需转换为第三类数据类型，否则可能带来递归。
CREATE FUNCTION equal(p1 boolean, p2 int)
RETURNS boolean WITH (NOT variant);
  DEFINE v_p1 CHAR(1);
  DEFINE v_p2 CHAR(1);
  LET v_p1 = CAST(p1 AS CHAR);
  LET v_p2 = CAST(p2 AS CHAR);
  IF (v_p1 IN ('t','1') AND v_p2 IN ('t','1')) 
      OR (v_p1 IN ('f','0') AND v_p2 IN ('f','0')) THEN 
    RETURN 't';
  ELSE
    RETURN 'f';
  END IF;
END FUNCTION;

DROP FUNCTION IF EXISTS notequal(boolean,int);
CREATE FUNCTION notequal(p1 boolean, p2 int)
RETURNS boolean WITH (NOT variant);
  DEFINE v_p1 CHAR(1);
  DEFINE v_p2 CHAR(1);
  LET v_p1 = CAST(p1 AS CHAR);
  LET v_p2 = CAST(p2 AS CHAR);
  IF (v_p1 IN ('t','1') AND v_p2 IN ('f','0')) 
      OR (v_p1 IN ('f','0') AND v_p2 IN ('t','1')) THEN 
    RETURN 't';
  ELSE
    RETURN 'f';
  END IF;
END FUNCTION;

DROP FUNCTION IF EXISTS equal(int,boolean);
CREATE FUNCTION equal(p2 int,p1 boolean)
RETURNS boolean WITH (NOT variant);
  RETURN equal(p1,p2);
END FUNCTION;

DROP FUNCTION IF EXISTS notequal(int,boolean);
CREATE FUNCTION notequal(p2 int,p1 boolean)
RETURNS boolean WITH (NOT variant);
  RETURN notequal(p1,p2);
END FUNCTION;

测试示例：

CREATE TABLE tabbool(col1 int, col2 boolean);
INSERT INTO tabbool values(1,1),(2,0),(3,-1),(4,null);
SELECT * FROM tabbool;
SELECT * FROM tabbool WHERE 0 != col2;
SELECT * FROM tabbool WHERE col2 = 0;
SELECT * FROM tabbool WHERE col2 is null;