Introduction to SQLite INTEGER Data Type

SQLite is a lightweight relational database management system widely used in embedded devices and mobile applications. SQLite supports various data types, including INTEGER, TEXT, REAL, BLOB, etc. This article will focus on the INTEGER data type.

Syntax

In SQLite, the INTEGER data type is used to store integer values. The syntax is as follows:

INTEGER[(N)]

where N represents the maximum number of digits for the integer. If N is not specified, the default maximum number of digits for an integer is 8 bytes.

Use Cases

The INTEGER data type is suitable for storing integer-type data such as user’s age, quantity of orders, number of article reads, etc. Compared to other data types, the INTEGER data type has the following advantages:

  • Small storage space: SQLite uses Variable-Length Integer Encoding (VLE) technique, which can save storage space.
  • Fast calculation speed: Integer types have faster calculation speed compared to floating-point types and string types.

Therefore, when storing integer-type data, using the INTEGER data type can improve the performance of the database.

Examples

Here are two examples illustrating how to use the INTEGER data type.

Example 1: Creating a table with INTEGER field

Suppose we want to create a table to store student information, including student ID (integer type), name (text type), and birthdate (text type). We can use the following SQL statement to create the table:

CREATE TABLE students (
  id INTEGER PRIMARY KEY,
  name TEXT,
  birthday TEXT
);

The id field in this table uses the INTEGER data type to store the student ID. Since id is a primary key, a unique value will be automatically assigned.

Example 2: Inserting and querying INTEGER data

Now that we have created a table with INTEGER field, let’s see how to insert and query data of this type.

First, we can use the following SQL statement to insert a student record into the table:

INSERT INTO students (id, name, birthday)
VALUES (10001, '张三', '2000-01-01');

This statement inserts a student record into the students table, with the id field using the INTEGER data type to store the student ID.

Next, we can use the following SQL statement to query the student ID and name of all students in the students table:

SELECT id, name FROM students;

This statement will return the student ID and name of all students in the students table.

Conclusion

The INTEGER data type is a commonly used data type in SQLite for storing integer-type data. Using the INTEGER data type can save storage space and improve calculation speed, thereby enhancing the performance of the database. When creating and manipulating tables with INTEGER fields, it is important to ensure data type matching to avoid data type errors and other exceptions. In addition, when using the INTEGER data type to store numeric data, it is advisable to avoid using negative numbers to ensure accuracy in calculations. In summary, using the INTEGER data type wisely can contribute to the performance improvement of SQLite databases.