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Asked: 2024-09-27T06:47:16+05:30 In:

how to concat string in postgresql

I’m working on a PostgreSQL database and I need to combine multiple string values into one, but I’m unsure how to do it effectively. I’ve seen different methods being mentioned online, and I’m a bit confused about which one to use.

For instance, I’ve read about using the `||` operator for concatenation, like this: `SELECT ‘Hello ‘ || ‘World’; However, I’m also aware that there’s a function called `CONCAT()` that can accomplish the same task. Can someone explain the differences between these two approaches? Are there specific scenarios where one is better than the other?

Additionally, I’m dealing with NULL values in my database, and I’m concerned about how that impacts the concatenation process. I’ve heard that using `||` may result in a NULL if any of the strings are NULL, but I’m not sure how `CONCAT()` handles that situation.

It would also be helpful if someone could provide examples or best practices for using these methods, especially when concatenating values from different columns in a table. Any insights on performance or readability would be greatly appreciated! Thank you!

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    2 Answers

    1. So, like, if you wanna join two strings in PostgreSQL, it’s kinda simple I think. You can use this thing called the `||` operator. It’s like a plus sign but for strings!

      Here’s how you can do it:

      SELECT 'Hello' || ' ' || 'World'; -- This will give you 'Hello World'

      You just put stuff on either side of the `||` and it will stick them together. Oh, and don’t forget the spaces if you need them! Like, I put a space between ‘Hello’ and ‘World’ so they’re not all squished together.

      Another way, I think, is to use the `CONCAT` function. It looks like this:

      SELECT CONCAT('Hello', ' ', 'World'); -- Yep, this also gives 'Hello World'

      It does the same thing, more or less, but in a different way. It’s kinda cool, right?

      So yeah, if you wanna join strings, just try these methods and see what works for ya!


    2. To concatenate strings in PostgreSQL, you can utilize the standard concatenation operator `||`. This operator allows you to combine two or more strings into one. For instance, if you have two text fields, `first_name` and `last_name`, you can concatenate them into a single string with a space in between using the following SQL query: `SELECT first_name || ‘ ‘ || last_name AS full_name FROM users;`. This method is straightforward and efficient for combining text values in your database queries.

      Alternatively, PostgreSQL also provides the `CONCAT()` function, which can be quite handy, especially when dealing with NULL values. Unlike the `||` operator that returns NULL if any operand is NULL, the `CONCAT()` function treats NULLs as empty strings. To achieve the same result as the previous example, you can use: `SELECT CONCAT(first_name, ‘ ‘, last_name) AS full_name FROM users;`. This flexibility can be advantageous in various scenarios where you might be concatenating user input or records that may have missing data.

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