如何在SQL查询中将SQL列的空值转换为0并将varchar转换为十进制

Question

我需要将varchar数据类型中的SQL列转换为decimal ，将null值转换为0。这是将varchar转换为decimal代码：

SELECT 
    CAST(debit as DECIMAL(9,2)),
    CAST(credit as DECIMAL(9,2)),
    sum_accname,
    sum_date, 
    sum_description
FROM 
    sum_balance

我需要将借方和贷方列的空值转换为零。 如何将空值转换部分插入此代码？

Answer 1

SELECT 
    COALESCE(CAST(debit as DECIMAL(9,2)),0) as debit,
    COALESCE(CAST(credit as DECIMAL(9,2)),0) as credit,
    sum_accname,
    sum_date, 
    sum_description
FROM 
    sum_balance

Answer 2

使用COALESCE函数获取NOT NULL值。

尝试这个：

SELECT 
    CAST(COALESCE(debit, '0') AS DECIMAL(9,2)),
    CAST(COALESCE(credit, '0') AS DECIMAL(9,2)),
    sum_accname,
    sum_date, 
    sum_description
FROM 
    sum_balance;

Answer 3

尝试这个

SELECT 
    CAST(isnull(debit ,0) as DECIMAL(9,2)),
    CAST(isnull(credit,0) as DECIMAL(9,2)),
    sum_accname,
    sum_date, 
    sum_description
FROM 
    sum_balance

Answer 4

改进的格式，对于sql server，有isull选项。
查询应该是这样的

SELECT isnull(CAST(debit as DECIMAL(9,2)),0), 
isnull(CAST(credit as DECIMAL(9,2)),0), sum_accname, sum_date, sum_description
FROM sum_balance