SQLite Learning Note 5: Inserting data, querying data, and deleting data

Zeng: All programming is data-centric, and it makes sense.

The so-called database database, no data called what database, then see how to insert data in the table.

One insert data

1 Creating a Table

To insert the data first, you need to create a table first:

CREATE TABLE Company (   ID int PRIMARY KEY isn't     null,   NAME           TEXT not    null,   age            INT     not NULL,   ADDRESS        CHAR (+),   SALARY         REAL);

2 First way: Specify columns

There are two basic formats for inserting data, the first of which is the specified column, and the syntax is as follows:

INSERT into table_name (column1, Column2, Column3,... columnn)]  VALUES (value1, value2, value3,... Valuen);

For example:

INSERT into Company (id,name,age,address,salary) VALUES (1, ' Hanfeng ', +, ' Hubei ', 10000.00);

In this way, only the NOT NULL column is given a value, and the other columns that are not specified can be empty

3 Second way: Full column

The second way to insert is to not know the column, but to specify a value for each column, it is important to note that the order must be consistent.

INSERT into table_name VALUES (value1, value2, value3,... Valuen);

Two data query

1 Querying the specified column

Query values a value for the specified column in a table:

SELECT column1, Column2, COLUMNN from table_name;

2 querying the values of all columns in a table

SELECT * FROM table_name;

3 Setting the output format

. Header on-Displays a list of. Mode column--sets the column to its

Three delete data

Basic syntax:

DELETE from Table_namewhere [condition];