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Asked: 2024-09-26T17:11:06+05:30 In:

which sql statement is used to return only different values

I’ve been working with SQL for a little while now, and I’ve reached a point where I need to optimize my queries to ensure I’m retrieving unique values from my database. The situation arises when I’m querying a table that contains duplicates, and I only want to get distinct entries for analysis. For instance, I have a ‘customers’ table, and I want to pull a list of unique cities where my customers are located without getting multiple entries for the same city.

I’ve heard about the `DISTINCT` keyword, but I’m a bit unsure about how to implement it properly in my SQL statements. Should I use it in conjunction with other clauses, like `WHERE` or `ORDER BY`? Also, are there any performance considerations I need to keep in mind when using `DISTINCT`, especially on large datasets? If I wanted to retrieve distinct values from specific columns, would I just apply `DISTINCT` to those columns only? I’m really seeking clarification on the best practices for using `DISTINCT` so that I can write more efficient and effective SQL queries. Can anyone provide some insight or examples of how to use this in different scenarios?

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    2 Answers

    1. So, like, if you want to get just the different values from a table in SQL, you can kinda use this thing called the SELECT statement. But here’s the cool part! You throw in the word DISTINCT to make sure you’re only getting those unique values. It’s like telling the database, “Hey, I just want the different stuff, okay?”

      Here’s a super simple example:

      SELECT DISTINCT column_name FROM table_name;

      You just put in the name of the column you’re looking at and the table’s name, and boom! You get the distinct values. Easy peasy, right?

    2. The SQL statement used to return only distinct or different values from a database table is the SELECT DISTINCT statement. This command is particularly useful when you want to eliminate duplicate entries in your query results. For example, if you have a table containing a list of employee records with a column for job titles, using SELECT DISTINCT job_title FROM employees; will yield a list of all unique job titles without repetitions. This can help in analyzing data or generating reports where distinct values are needed.

      In addition to filtering duplicates, the SELECT DISTINCT statement can be combined with other clauses, such as ORDER BY to sort the results, or WHERE to filter data based on specific conditions. For instance, SELECT DISTINCT department FROM employees WHERE salary > 50000 ORDER BY department; would return a sorted list of unique departments for employees earning above a specified salary. Leveraging this command effectively allows for clearer insights and more concise data presentations.

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