Detect if value is number in MySQL

问题

Is there a way to detect if a value is a number in a MySQL query? Such as

SELECT * 
FROM myTable 
WHERE isANumber(col1) = true

回答1:

This should work in most cases.

SELECT * FROM myTable WHERE concat('',col1 * 1) = col1

It doesn't work for non-standard numbers like

1e4
1.2e5
123. (trailing decimal)

回答2:

You can use Regular Expression too... it would be like:

SELECT * FROM myTable WHERE col1 REGEXP '^[0-9]+$';

Reference: http://dev.mysql.com/doc/refman/5.1/en/regexp.html

回答3:

If your data is 'test', 'test0', 'test1111', '111test', '111'

To select all records where the data is a simple int:

SELECT * 
FROM myTable 
WHERE col1 REGEXP '^[0-9]+$';

Result: '111'

(In regex, ^ means begin, and $ means end)

To select all records where an integer or decimal number exists:

SELECT * 
FROM myTable 
WHERE col1 REGEXP '^[0-9]+\\.?[0-9]*$'; - for 123.12

Result: '111' (same as last example)

Finally, to select all records where number exists, use this:

SELECT * 
FROM myTable 
WHERE col1 REGEXP '[0-9]+';

Result: 'test0' and 'test1111' and '111test' and '111'

回答4:

This answer is similar to Dmitry, but it will allow for decimals as well as positive and negative numbers.

select * from table where col1 REGEXP '^[[:digit:]]+$'

回答5:

SELECT * FROM myTable
WHERE col1 REGEXP '^[+-]?[0-9]*([0-9]\\.|[0-9]|\\.[0-9])[0-9]*(e[+-]?[0-9]+)?$'

Will also match signed decimals (like -1.2, +0.2, 6., 2e9, 1.2e-10).

Test:

drop table if exists myTable;
create table myTable (col1 varchar(50));
insert into myTable (col1) 
  values ('00.00'),('+1'),('.123'),('-.23e4'),('12.e-5'),('3.5e+6'),('a'),('e6'),('+e0');

select 
  col1,
  col1 + 0 as casted,
  col1 REGEXP '^[+-]?[0-9]*([0-9]\\.|[0-9]|\\.[0-9])[0-9]*(e[+-]?[0-9]+)?$' as isNumeric
from myTable;

Result:

col1   |  casted | isNumeric
-------|---------|----------
00.00  |       0 |         1
+1     |       1 |         1
.123   |   0.123 |         1
-.23e4 |   -2300 |         1
12.e-5 | 0.00012 |         1
3.5e+6 | 3500000 |         1
a      |       0 |         0
e6     |       0 |         0
+e0    |       0 |         0

Demo

回答6:

use a UDF (user defined function).

CREATE FUNCTION isnumber(inputValue VARCHAR(50))
  RETURNS INT
  BEGIN
    IF (inputValue REGEXP ('^[0-9]+$'))
    THEN
      RETURN 1;
    ELSE
      RETURN 0;
    END IF;
  END;

Then when you query

select isnumber('383XXXX')

--returns 0

select isnumber('38333434')

--returns 1

select isnumber(mycol) mycol1, col2, colx from tablex; -- will return 1s and 0s for column mycol1

--you can enhance the function to take decimals, scientific notation , etc...

The advantage of using a UDF is that you can use it on the left or right side of your "where clause" comparison. this greatly simplifies your SQL before being sent to the database:

 SELECT * from tablex where isnumber(columnX) = isnumber('UnkownUserInput');

hope this helps.

回答7:

Returns numeric rows

I found the solution with following query and works for me:

SELECT * FROM myTable WHERE col1 > 0;

This query return rows having only greater than zero number column that col1

Returns non numeric rows

if you want to check column not numeric try this one with the trick (!col1 > 0):

SELECT * FROM myTable WHERE !col1 > 0;

回答8:

Another alternative that seems faster than REGEXP on my computer is

SELECT * FROM myTable WHERE col1*0 != col1;

This will select all rows where col1 starts with a numeric value.

回答9:

Still missing this simple version:

SELECT * FROM myTable WHERE `col1` + 0 = `col1`

(addition should be faster as multiplication)

Or slowest version for further playing:

SELECT *, 
CASE WHEN `col1` + 0 = `col1` THEN 1 ELSE 0 END AS `IS_NUMERIC` 
FROM `myTable`
HAVING `IS_NUMERIC` = 1

回答10:

I recommend: if your search is simple , you can use `

column*1 = column

` operator interesting :) is work and faster than on fields varchar/char

SELECT * FROM myTable WHERE column*1 = column;

ABC*1 => 0 (NOT EQU **ABC**)
AB15*A => 15 (NOT EQU **AB15**)
15AB => 15 (NOT EQU **15AB**)
15 => 15 (EQUALS TRUE **15**)

回答11:

SELECT * FROM myTable WHERE sign (col1)!=0

ofcourse sign(0) is zero, but then you could restrict you query to...

SELECT * FROM myTable WHERE sign (col1)!=0 or col1=0

UPDATE: This is not 100% reliable, because "1abc" would return sign of 1, but "ab1c" would return zero... so this could only work for text that does not begins with numbers.

回答12:

you can do using CAST

  SELECT * from tbl where col1 = concat(cast(col1 as decimal), "")

回答13:

I have found that this works quite well

if(col1/col1= 1,'number',col1) AS myInfo

回答14:

Try Dividing /1

select if(value/1>0 or value=0,'its a number', 'its not a number') from table

来源：https://stackoverflow.com/questions/5064977/detect-if-value-is-number-in-mysql

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mysql

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where-clause