How to Specify a Date Format on Creating a Table and Inserting Values in SQL?

Dates are a fundamental part of database management, as they provide a timeline for analyzing data trends, tracking records, and scheduling events. In SQL, handling and formatting date columns correctly ensures consistency and clarity in our database. One critical aspect of working with dates is specifying their format while creating a table and inserting values.

Data Types for Handling Dates in SQL

SQL provides several data types for handling dates and times:

• DATE: Stores date values (e.g., year, month, day).
  
• DATETIME: Stores both date and time values (e.g., year, month, day, hour, minute, second).
  
• TIMESTAMP: Similar to DATETIME but with additional precision (e.g., fractional seconds or time zones).

1. Creating a Table with a Date Fields

To define a date column in a table, use the appropriate data type (e.g., DATE, DATETIME) during table creation. Below are examples:

Example 1: Table with a Simple Date Field

To demonstrate, let’s create a table called Employees that stores user information, including EmployeeID, Name and HireDate. Here, we also have created a column named Dt_FORMATTED where we are going to save our formatted Date

CREATE TABLE Employees (
    EmployeeID INT PRIMARY KEY,
    Name VARCHAR(100),
    HireDate DATE
);

Example 2: Table with a Formatted Date Column Using CONVERT()

Now, we see the CONVERT() function. The CONVERT() function simply converts a value of any type into a specified datatype. By using this function, we are casting the string to a date. In the place of style argument, we have mentioned '104'. It is a numeric code to specify the date format.

Syntax

CONVERT ( data_type ( length ) ,
expression , style )  

Query:

CREATE TABLE GFG_User (
    Id INT NOT NULL,
    Dt DATE,
    Address VARCHAR(100),
    Dt_FORMATTED AS (CONVERT(VARCHAR(255), Dt, 104)),   
    PRIMARY KEY (Id)
);

Explanation:

• CONVERT() converts the Dt column into a German date format (dd.mm.yyyy) and saves it in Dt_FORMATTED.
• The 104 style code specifies the German format.

2. Inserting Dates into the Table with Specific Formats

When inserting dates into a table, it’s important to specify the correct format. SQL uses the SET DATEFORMAT command to interpret date strings correctly

Query:

SET DATEFORMAT dmy; INSERT INTO GFG_user
(Id, Dt, Address) VALUES ('1','23.11.2021',
'German');   

Explanation:

• The SET DATEFORMAT dmy command ensures the date string is interpreted as day.month.year.
  
• Without this, SQL Server might assume a default month.day.year format, leading to errors.

Common Error Avoidance

• For example, suppose we are trying to insert 06.07.2000. The server is unable to detect if the date is the 6th of July or it is the 7th of June.
  
• Though it uses the localization settings of the user account that is operating to figure out .
  
• Not mentioning the DATEFORMAT might give us an error as most of the times the account that is running the operation is set to USA format, that is Month Day Year (mdy).
  
• The error was caused because we wanted to save it as dmy, not mdy. However, using DATEFORMAT will help us to get rid of it.

Output

3. Using TO_DATE() for Custom Formats (Oracle)

For databases like Oracle, TO_DATE() function is commonly used to specify and insert dates in a particular format. TO_DATE() function converts strings into dates using a specified format. We can also insert date using 'to_date' function in sql. The following syntax can be used:

Syntax:

TO_DATE([value], [format]);

Example

Let’s create another table called GFG_Intern to demonstrate the use of TO_DATE(). Format of date can be of different types such as: 'dd-mm-yyyy', 'yyyy-mm-dd', 'mm-dd-yyyy'.

CREATE TABLE GFG_Intern (
    e_name VARCHAR(20),
    e_id NUMBER,
    joiningDate DATE
);

INSERT INTO GFG_Intern VALUES ('FirstIntern', 1, TO_DATE('2022-12-12', 'yyyy-mm-dd'));  
INSERT INTO GFG_Intern VALUES ('SecondIntern', 2, TO_DATE('2022-Dec-12', 'yyyy-mm-dd'));  
INSERT INTO GFG_Intern VALUES ('ThirdIntern', 3, TO_DATE('30-12-2022', 'dd-mm-yyyy'));  

SELECT * FROM GFG_INTERN;

Output

Explanation:

• TO_DATE('2022-12-12', 'YYYY-MM-DD'): Converts the string into a date object using the specified format.
  
• Multiple date formats like DD-Mon-YYYY, DD-MM-YYYY, and MM-DD-YYYY can be used based on your requirements.

4. Viewing and Formatting Date Queries

We can format or manipulate date columns in queries using functions like CONVERT(), TO_DATE(), YEAR(), and more.

SQL Server Example:

SELECT Id, Dt, FORMAT(Dt, 'dd MMM yyyy') AS FormattedDate FROM GFG_User;

Oracle Example:

SELECT e_name, TO_CHAR(joiningDate, 'DD-Mon-YYYY') AS FormattedDate FROM GFG_Intern;

Output

Common Date Format Codes in SQL

Check this table to see different codes used for different formats:

Conclusion

Specifying a date format while creating and populating a table in SQL is essential for maintaining data consistency and avoiding errors. By using commands like SET DATEFORMAT, functions like CONVERT() and TO_DATE(), and best practices, we can manage dates effectively in our database. Implementing these techniques will not only streamline our operations but also ensure our database remains accurate and easy to understand

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Article Tags :

• SQL
• Databases
• SQL-Server
• SQL-Query