How to convert characters to date in Oracle

Oracle is a popular relational database management system capable of processing large amounts of data and transactions. In Oracle database, sometimes it is necessary to convert character type time to date format. In this article, we will introduce how to convert characters to dates in Oracle.

First of all, we need to understand what built-in functions are available in Oracle for date and time processing.

1. TO_CHAR: Convert date or time to string type.
2. TO_DATE: Convert a string type date or time to a date type.
3. SYSDATE: Returns the current system date and time.
4. ADD_MONTHS: Add months to the date.
5. MONTHS_BETWEEN: Calculates the number of months between two dates.

Next let’s take a look at how to use the TO_DATE function to convert character type time to date format.

SELECT TO_DATE('2022-02-22', 'YYYY-MM-DD') FROM dual;

In the above example, we convert the character type time '2022-02-22' into date format, and 'YYYY-MM-DD' is the formatted string of date format.

If the character type time we need to convert contains time information, we can change the format string to 'YYYY-MM-DD HH24:MI:SS', where HH24 represents hours, MI represents minutes, and SS Represents seconds.

SELECT TO_DATE('2022-02-22 20:15:30', 'YYYY-MM-DD HH24:MI:SS') FROM dual;

In the above example, we successfully converted the character type time '2022-02-22 20:15:30' to date format.

In addition, if we don’t want to repeatedly use the TO_DATE function to convert time formats in query statements, we can use date format columns when creating the table, so that we can directly insert character type time into date type in the column.

For example:

CREATE TABLE sales (
    sale_id NUMBER(10),
    sale_date DATE,
    sale_amount NUMBER(10,2)
);

INSERT INTO sales (sale_id, sale_date, sale_amount)
VALUES (1, TO_DATE('2022-02-22 20:15:30', 'YYYY-MM-DD HH24:MI:SS'), 1000);

In the above example, we created a table named "sales", which contains three fields: sales ID, sales date and sales amount. When we inserted data, we inserted the character type time '2022-02-22 20:15:30' into the date type column "sale_date".

In Oracle, the processing of date and time is very important, because many business operations require the use of date and time. Knowing how to work with dates and times is one of the essential skills to become a good Oracle developer and administrator. This article introduces how to use the TO_DATE function to convert character type time to date format, and gives an example of inserting time when inserting data.

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