MySQL string field to floating point field

mysql The conversion type uses two functions ：CONVERT（ Field / The values that need to be converted , type ） CAST（ Field / The values that need to be converted AS type ）

Because the previous design , Set the amount field type of a table to varchar

Now you need to use this table according to the user , And the type of table data .

When calculating , You need to convert the type .

Just started using CONVERT(jo.`pay_money`, DECIMAL)   This way , The output result is an integer .

Afterthought DECIMAL Declaration syntax of DECIMAL(M,D)

·M Is the maximum number of numbers （ precision ）. Its scope is 1～65（ In the older MySQL In the version , The allowable range is 1～254）.

·D Is the number of digits to the right of the decimal point （ scale ）. Its scope is 0～30, But not more than M.

The default number of decimal places reserved is 0

Estimate and modify type conversion sql ：CONVERT( Field , DECIMAL( Value length , Keep a few decimal places ))