javascript mysql data type conversion

In front-end development, it is often necessary to convert the data types of the front-end and back-end. Among them, JavaScript and MySQL are two commonly used languages. This article will talk about the conversion between JavaScript and MySQL data types.

1. JavaScript data types

JavaScript is a dynamically typed language, which means that you do not need to specify a data type when defining a variable, and the data type can be automatically inferred. There are mainly the following data types in JavaScript:

1. Numeric type

In JavaScript, all values ​​are floating point. It can be expressed in integers, decimals, and scientific notation. For example: 1, 3.14, 2e5.

2. String type

Use quotation marks (single quotation marks or double quotation marks) to represent a string. For example: 'hello', "world".

3. Boolean type

The Boolean type has only two values: true and false.

4. null and undefined

null represents a null object pointer; undefined represents an undefined value.

5. Object type

An object in JavaScript is an unordered set of properties. Including arrays, functions, dates and other objects.

2. MySQL data type

MySQL is a relational database management system. In MySQL, data types can be classified into the following categories:

1. Integer type

For example: TINYINT, SMALLINT, MEDIUMINT, INT, BIGINT.

2. Floating point type

For example: FLOAT, DOUBLE.

3. String type

For example: CHAR, VARCHAR, TEXT.

4. Date and time type

For example: DATE, TIME, DATETIME, TIMESTAMP.

5. Enumeration and collection types

For example: ENUM and SET.

3. Conversion between JavaScript and MySQL data types

In front-end development, we often need to store the value of JavaScript variables in the database, or read data from the database and assign values. Give JavaScript variables. At this time, conversion between JavaScript and MySQL data types is required.

1. Convert JavaScript numeric type to MySQL numeric type

If you need to convert the numeric type in JavaScript to the numeric type in MySQL, you can use the valueOf( of Number type ) method to convert the numeric type in JavaScript into the MySQL numeric type. For example:

var num = 123;
var mysql_num = Number(num).valueOf();

2. Convert JavaScript string type to MySQL string type

If you need to convert JavaScript string type to MySQL string type, you can use The toString() method of the String type converts the JavaScript string type into the MySQL string type. For example:

var str = 'hello';
var mysql_str = String(str).toString();

3. Convert JavaScript Boolean type to MySQL numeric type

If you need to convert JavaScript Boolean type to MySQL numeric type, you can use numeric operators to convert Convert Boolean type value to numeric value. For example:

var bool = true;
var mysql_num = +bool;

4. Convert MySQL string type into JavaScript string type

If you need to convert MySQL string type into JavaScript string type, you can use The toString() method of the String type converts the MySQL string type into the JavaScript string type. For example:

var mysql_str = 'world';
var str = String(mysql_str).toString();

5. Convert MySQL numeric type into JavaScript numeric type

If you need to convert MySQL numeric type into JavaScript numeric type, you can use valueOf of Number type () method, convert MySQL numeric type into JavaScript numeric type. For example:

var mysql_num = 123;
var num = Number(mysql_num).valueOf();

The above is the conversion between JavaScript and MySQL data types. In actual development, data interaction between different systems may involve more type conversions. Conversions need to be made on a case-by-case basis.

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