Sharing of data type conversion methods in MySQL

MySQL is a widely used open source relational database. It supports a variety of data types, including integers, strings, dates and times, etc. In practical applications, we often need to convert different data types to meet various needs. This article will share the data type conversion methods in MySQL, including implicit conversion and explicit conversion.

1. Implicit conversion

Most data types in MySQL can be implicitly converted, that is, they are automatically converted to the appropriate type during operation. Let's demonstrate it through an example:

1. Convert date type data to character type

Suppose we have an orders order table, in which there is an The date field is order_date. If we want to convert this field to character data, we can use the CAST or CONVERT function, as follows:

SELECT CAST(order_date AS CHAR) FROM orders;
SELECT CONVERT(order_date, CHAR) FROM orders;

2. Convert character data to integer type

Suppose we have a items product table, in which there is a character field price, which represents the product price. If we want to convert this field to integer data, we can use the CAST or CONVERT function, as follows:

SELECT CAST(price AS UNSIGNED) FROM items;
SELECT CONVERT(price, UNSIGNED) FROM items;

2. Explicit conversion

In addition to implicit conversion, MySQL also supports explicit conversion, that is, converting one data type to another data type through a function. Let's demonstrate it through an example:

1. Convert integer data to character type

Suppose we have a customers customer table, in which there is a The integer field is cust_id. If we want to convert this field to character data, we can use the CAST or CONVERT function, as follows:

SELECT CAST(cust_id AS CHAR) FROM customers;
SELECT CONVERT(cust_id, CHAR) FROM customers;

2. Convert character data to date type

Suppose we have an orders order table, in which there is a character field order_date_str, which represents the order date (such as "2021-09-30" ). If we want to convert this field to date type data, we can use the STR_TO_DATE function, as follows:

SELECT STR_TO_DATE(order_date_str, '%Y-%m-%d') FROM orders;

3. Convert date type data to character type

Suppose we have an orders order table, which has a date field of order_date. If we want to convert this field into character data in a specified format, we can use the DATE_FORMAT function, as follows:

SELECT DATE_FORMAT(order_date, '%Y-%m-%d %H:%i:%s') FROM orders;

The above is the data type conversion method in MySQL, including implicit conversion and Explicit conversion. In practical applications, these methods need to be used flexibly according to specific needs to achieve the best results.

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