PostgreSQL MAKE_TIME Date/Time Function

PostgreSQL MAKE_TIME Date/Time Function

The PostgreSQL MAKE_TIME function is used to create a time value from specified hour, minute, and seconds fields. This function is essential for constructing time values from individual components, which can be useful in various time-based calculations and data manipulations.

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Syntax

MAKE_TIME(hour int, min int, sec double precision)

The MAKE_TIME function has the following components:

• hour: The hour component of the time.
• min: The minute component of the time.
• sec: The seconds component of the time.

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Example PostgreSQL MAKE_TIME Queries

Let's look at some examples of PostgreSQL MAKE_TIME function queries:

1. Basic MAKE_TIME Example

SELECT MAKE_TIME(8, 15, 23.5) AS constructed_time;

This query creates a time from the hour 8, minute 15, and seconds 23.5, resulting in '08:15:23.5'.

2. MAKE_TIME with Whole Seconds

SELECT MAKE_TIME(12, 0, 0) AS constructed_time;

This query creates a time from the hour 12, minute 0, and seconds 0, resulting in '12:00:00'.

3. MAKE_TIME with Column Values

SELECT id, name, MAKE_TIME(hour, minute, second) AS log_time
FROM logs;

This query retrieves the id, name, and constructs a log time from the hour, minute, and second columns for each row in the logs table.

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Full Example

Let's go through a complete example that includes creating a table, inserting data, and using the MAKE_TIME function to construct time values from individual components.

Step 1: Creating a Table

This step involves creating a new table named logs to store log data, including their time components.

CREATE TABLE logs (
    id SERIAL PRIMARY KEY,
    name TEXT,
    hour INT,
    minute INT,
    second DOUBLE PRECISION
);

In this example, we create a table named logs with columns for id, name, hour, minute, and second.

Step 2: Inserting Data into the Table

This step involves inserting some sample data into the logs table.

INSERT INTO logs (name, hour, minute, second)
VALUES ('Log1', 8, 15, 23.5),
       ('Log2', 12, 0, 0),
       ('Log3', 18, 45, 30.75);

Here, we insert data into the logs table.

Step 3: Using the MAKE_TIME Function

This step involves using the MAKE_TIME() function to construct time values from the individual components in the logs table.

Construct log time from hour, minute, and second columns:

SELECT id, name, MAKE_TIME(hour, minute, second) AS log_time
FROM logs;

This query constructs the log time from the hour, minute, and second columns for each row in the logs table.

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Conclusion

The PostgreSQL MAKE_TIME() function is a fundamental tool for constructing time values from individual hour, minute, and second components. Understanding how to use the MAKE_TIME() function and its syntax is essential for accurate time construction in PostgreSQL databases.