oracle oracle中如何将整数转换为十进制
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How to Convert integer to decimal in oracle
提问by End.Game
how can i convert a integer to decimal in oracle? Is there any function like TO_CHAR? I need to put this function on a where clause. Thanks
oracle中如何将整数转换为小数？有没有像 TO_CHAR 这样的函数？我需要将此函数放在 where 子句上。谢谢
SELECT IDDS,
ID
FROM T_TABLEONE
WHERE CAST(ID as DECIMAL)='1,301131832E19';
采纳答案by David Aldridge
If you apply a function to the column then you can run the risks of:
如果对列应用函数，则可能会面临以下风险：
- being unable to use a regular index on that column
- obscuring the expected cardinality of the result set, which can cause query optimisation problems.
- 无法在该列上使用常规索引
- 模糊结果集的预期基数，这可能会导致查询优化问题。
So it's generally a bad practice, and you'd do better to cast your literal to the same type as the column, in this case using to_number().
所以这通常是一个不好的做法，你最好将你的文字转换为与列相同的类型，在这种情况下使用 to_number()。
However in this case I'm surprised that it's necessary, as Oracle's type conversion in recent releases should be able to cope with comparing an integer column to a number expressed in scientific notation: http://sqlfiddle.com/#!4/336d3/8
但是，在这种情况下，我很惊讶这是必要的，因为最近版本中的 Oracle 类型转换应该能够处理将整数列与以科学记数法表示的数字进行比较：http: //sqlfiddle.com/#!4/336d3 /8
