Скачать или смотреть How to Concatenate Column Values from Multiple Rows in Oracle SQL

Discover how to efficiently concatenate values from multiple rows in Oracle SQL using LISTAGG to achieve your desired result.
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Concatenating Column Values from Multiple Rows in Oracle SQL

In the world of database management, there are times when you need to consolidate data from multiple rows into a single output. This is particularly useful in reporting and data analysis where summarizing related information is key. In this post, we are going to explore how to concatenate column values from multiple rows in Oracle SQL based on an ID column.

The Problem

Imagine you have a table with the following structure, where you store levels associated with various IDs:

IDLevel000C000FK111F222FN222C333F333C444CYou want to transform this data into a new format where multiple values in the Level column are concatenated into a single string for each ID. The expected result would look like this:

IDLevel000C - FK111F222FN - C333F - C444CThe Solution

To achieve this result in Oracle SQL, we can utilize the LISTAGG function. This function allows us to concatenate values from multiple rows into a single string with a specified delimiter. Let's break down the steps you'll need to follow.

Sample Data Setup

First, we need to set up the sample data that replicates your table. You can run the following SQL statement to create a temporary table (or use your existing one):

[[See Video to Reveal this Text or Code Snippet]]

The Query

Now that we have our data in a temporary setup, we can write the main query using LISTAGG. Below is the SQL statement you need:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Query

SELECT Clause: We select the id column and use LISTAGG to concatenate values from the c_level column.

LISTAGG Function:

The first parameter is the column you want to concatenate (c_level).

The second parameter specifies the delimiter used for concatenation (' - ' in this case).

WITHIN GROUP (ORDER BY NULL) indicates that the order of concatenation does not matter in this example.

GROUP BY Clause: This groups the results by id, ensuring each ID has its levels concatenated together.

ORDER BY Clause: Ensures the final result is sorted by id.

Result of the Query

When you run the query above, you should receive the expected output:

IDRESULT000C - FK111F222FN - C333F - C444CConclusion

Concatenating column values from multiple rows in Oracle SQL can greatly enhance your data presentation and reporting capabilities. By leveraging the LISTAGG function, you can efficiently create cohesive strings from fragmented data sets. This is particularly useful for summarizing and synthesizing information for better insights.

If you find this post helpful, be sure to check out more SQL tips and tricks to enhance your data manipulation skills. Happy querying!