Question

我正在使用Informix，并在查询中有一个CASE语句，如下所示：

CASE 
 when l.src_country = 'USA' then tl.cat--prodUSA.description
 when l.src_country = 'CAN' AND tl.fuel_type > 0 then tl.fuel_type
 when l.src_country = 'CAN' and tl.fuel_type = 0 and tl.cat in ("DEF","DEFD") then 4194304
 when l.src_country = 'CAN' and tl.fuel_type = 0 and tl.cat not in ("DEF","DEFD") then tl.fuel_type
 else 0
 END as product_code

在上面的陈述中，"tl.cat"属于CHAR类型＆amp; "tl.fuel_type"的类型为INT。

我需要做这样的事情：

CASE 
 when l.src_country = 'USA' then tl.cat--prodUSA.description
 when l.src_country = 'CAN' AND tl.fuel_type > 0 then tl.fuel_type :: CHARACTER
 when l.src_country = 'CAN' and tl.fuel_type = 0 and tl.cat in ("DEF","DEFD") then 4194304
 when l.src_country = 'CAN' and tl.fuel_type = 0 and tl.cat not in ("DEF","DEFD") then tl.fuel_type :: CHARACTER
 else 0
 END as product_code

但是当我尝试它时，我得到以下错误：

Corresponding data types must be compatible in CASE expression or DECODE function. [SQL State=IX000, DB Errorcode=-800]

当我尝试这个时：

CASE
when l.src_country = 'USA' then tl.cat--prodUSA.description
when l.src_country = 'CAN' AND tl.fuel_type > 0 then tl.fuel_type :: CHAR
when l.src_country = 'CAN' and tl.fuel_type = 0 and tl.cat in ("DEF","DEFD") then '4194304'
when l.src_country = 'CAN' and tl.fuel_type = 0 and tl.cat not in ("DEF","DEFD") then tl.fuel_type :: CHAR
else '0'
END as product_code

我收到以下错误：

Converted value does not fit into the allotted space

我需要将tl.fuel_type视为角色。我在这里做错了什么？

Answer 1

假设我们有一个像这样的表设置：

DROP TABLE IF EXISTS fuel_info;
CREATE TEMP TABLE fuel_info
(
    src_country    CHAR(3) NOT NULL,
    fuel_type      INTEGER NOT NULL,
    cat            CHAR(9) NOT NULL
);

INSERT INTO fuel_info VALUES('USA', 12, 'CAT1');
INSERT INTO fuel_info VALUES('CAN', 10, 'ABC2');
INSERT INTO fuel_info VALUES('CAN',  0, 'DEFD');
INSERT INTO fuel_info VALUES('CAN',  0, 'WXYZ');
INSERT INTO fuel_info VALUES('EUR',  1, 'P3X9');

我们可以调整问题中的表达式来重现问题。例如：

SELECT 
    CASE
    WHEN tl.src_country = 'USA' THEN tl.cat--prodUSA.description
    WHEN tl.src_country = 'CAN' AND tl.fuel_type > 0 THEN tl.fuel_type::CHAR
    WHEN tl.src_country = 'CAN' AND tl.fuel_type = 0 AND tl.cat IN ("DEF","DEFD") THEN '4194304'
    WHEN tl.src_country = 'CAN' AND tl.fuel_type = 0 AND tl.cat NOT IN ("DEF","DEFD") THEN tl.fuel_type::CHAR
    ELSE '0'
    END AS product_code
  FROM fuel_info AS tl;

这会生成SQL -1207: Converted value does not fit into the allotted space错误。

您可以通过为CHAR类型转换指定足够大的长度来修复它：

SELECT 
    CASE
    WHEN tl.src_country = 'USA' THEN tl.cat--prodUSA.description
    WHEN tl.src_country = 'CAN' AND tl.fuel_type > 0 THEN tl.fuel_type::CHAR(7)
    WHEN tl.src_country = 'CAN' AND tl.fuel_type = 0 AND tl.cat IN ("DEF","DEFD") THEN '4194304'
    WHEN tl.src_country = 'CAN' AND tl.fuel_type = 0 AND tl.cat NOT IN ("DEF","DEFD") THEN tl.fuel_type::CHAR(7)
    ELSE '0'
    END AS product_code
  FROM fuel_info AS tl;

这有效，产生：

CASE语句中的数据类型转换

1 个答案: