SQL – Create Table

To create a table in SQL, you can use the CREATE TABLE statement. Here is an example of how to create a table named “employees” with columns for “id”, “name”, “age”, and “salary”: SQL – Create Table

CREATE TABLE employees (
  id INT PRIMARY KEY,
  name VARCHAR(50) NOT NULL,
  age INT NOT NULL,
  salary DECIMAL(10, 2) NOT NULL
);

This example creates a table named “employees” with four columns:

  • “id” is an integer and is set as the primary key for the table. A primary key is a unique identifier for each row in the table, and it cannot contain null values.
  • “name” is a variable-length string with a maximum length of 50 characters, and it cannot contain null values.
  • “age” is an integer and it cannot contain null values.
  • “salary” is a decimal number, with a maximum of 10 digits and 2 digits after the decimal point, and it cannot contain null values.

You can also specify other options like AUTO_INCREMENT, DEFAULT value, UNIQUE constraint, FOREIGN KEY constraint etc.

Here is an example of how to create a table with auto increment and foreign key:

CREATE TABLE orders (
  order_id INT PRIMARY KEY AUTO_INCREMENT,
  customer_id INT NOT NULL,
  order_date DATE NOT NULL,
  FOREIGN KEY (customer_id) REFERENCES customers(customer_id)
);

In this example, “order_id” is the primary key and auto increment and “customer_id” is a foreign key that references to the “customer_id” in the “customers” table.

Please note that the exact syntax may vary depending on the SQL server you are using.

Also, make sure you have appropriate permissions to create a table in the database you want to create the table in.

Steps to Follow before create a table in SQL

There are several conditions that need to be met in order to create a table in SQL:

  1. You must have the necessary permissions to create a table in the database.
  2. The table name must be unique within the database.
  3. You must specify the columns for the table, along with their data types and any constraints.
  4. If you want to create a primary key, it must consist of one or more columns, and it must contain unique and non-null values.
  5. If you want to create a foreign key, it must reference a primary key in another table.
  6. If you want to specify a default value for a column, the default value must be compatible with the data type of the column.
  7. If you want to specify a check constraint, the constraint must evaluate to a Boolean value.
  8. If you are creating a table with a partition scheme, you must have the appropriate permissions and the partition scheme must be compatible with the data type of the partitioned column.
  9. If you are creating a table with a filegroup, the filegroup must exist before you create the table and the table must be compatible with the filegroup.
  10. You must ensure that the table name and column names do not exceed their maximum length, and that they follow the naming rules of your SQL server.

Please note that the specific requirements for creating a table may vary depending on the SQL server you are using.

Also, it is important to have a good understanding of the data you want to store in the table and the relationships with other tables before you design your table. This will help you to create a well-structured and efficient table that meets your needs.

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