How can multiple rows be combined into one row based on the value in the first column?

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One way to combine multiple rows into one row based on the value in the first column is to use the GROUP BY clause in SQL queries. The GROUP BY clause groups rows based on a shared value in a specific column, and then applies an aggregate function to each group to generate a single value for that group.

For example, consider a table with three columns: ID, Name, and Age. The table contains multiple rows with the same ID value, but different Name and Age values. To combine these rows into one row per ID, we can use the following SQL query:

SELECT ID, GROUPCONCAT(Name), AVG(Age) FROM tablename GROUP BY ID;

This query groups all the rows with the same ID value, concatenates the Name values into one string using the GROUP_CONCAT function, and calculates the average Age value for each group. The result is a table with one row per ID value, where the Name column contains a comma-separated list of all the names associated with that ID, and the Age column contains the average age for that group.