What is the usage of the MySQL convert function?

The CONVERT function in MySQL is used to transform an expression into a specified data type. It can be used to convert various data types such as numbers, dates, times, and strings.

Basic syntax:
CONVERT(expression, type)

Explanation of parameters:

1. the expression to be converted.
2. type: the type of data to convert.

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1. Convert the string ‘123’ to an integer type:
   SELECT CONVERT(‘123’, SIGNED);
2. Convert the date string ‘2022-01-01’ to a date type in SQL:
   SELECT CONVERT(‘2022-01-01’, DATE);
3. Convert the floating point number 2.5 to an integer using the following code:
   SELECT CONVERT(2.5, UNSIGNED);
4. Convert the integer 10 to a string type:
   SELECT CAST(10 AS CHAR);

Important points to note:

1. The CONVERT function does not modify the data type of the original expression, but instead returns the converted result.
2. The outcome of the conversion may vary depending on the target data type, such as the truncation of decimal places or changes in date formats.
3. If the conversion cannot be done effectively, the CONVERT function may return NULL or an error.

For more detailed information about the CONVERT function, please refer to the official MySQL documentation.