How can you make sure that your SQL scripts will be easy to read and maintain?

How do you make a SQL readable?

10 Best Practices to Write Readable and Maintainable SQL Code

  1. Use Uppercase for the Keywords. …
  2. Use Snake Case for the schemas, tables, columns. …
  3. Use aliases when it improves readability. …
  4. Formatting: Carefully use Indentation & White spaces. …
  5. Avoid Select * …
  6. Go for the ANSI-92 JOIN Syntax. …
  7. Use Common Table Expression (CTE)

How would you make SQL reads faster?

How To Speed Up SQL Queries

  1. Use column names instead of SELECT * …
  2. Avoid Nested Queries & Views. …
  3. Use IN predicate while querying Indexed columns. …
  4. Do pre-staging. …
  5. Use temp tables. …
  6. Use CASE instead of UPDATE. …
  7. Avoid using GUID. …
  8. Avoid using OR in JOINS.

How do you make SQL queries more efficient?

12 Tips to Write Efficient SQL Queries

  1. Create Small Batches of Data for Deletion and Updation. …
  2. Use CASE instead of UPDATE. …
  3. Use Temp Tables. …
  4. Avoid Using Another Developer’s Code. …
  5. Avoid Negative Searches. …
  6. Use The Exact Number of Columns. …
  7. No Need to Count Everything in the Table. …
  8. Avoid Using Globally Unique Identifiers.
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How do you keep SQL code clean?

Let’s dive into it:

  1. Programming Style. If you think that your programming style is trivial for SQL, think again. …
  2. Modularize Code via Common Table Expressions. …
  3. Variable Naming Conventions. …
  4. Simplify Code Using Temporary Functions. …
  5. Write Useful Comments.

Which join is faster in SQL?

You may be interested to know which is faster – the LEFT JOIN or INNER JOIN. Well, in general INNER JOIN will be faster because it only returns the rows matched in all joined tables based on the joined column.

Does limit make query faster?

The answer, in short, is yes. If you limit your result to 1, then even if you are “expecting” one result, the query will be faster because your database wont look through all your records. It will simply stop once it finds a record that matches your query.

Do joins slow down query?

Joins: If your query joins two tables in a way that substantially increases the row count of the result set, your query is likely to be slow. There’s an example of this in the subqueries lesson. Aggregations: Combining multiple rows to produce a result requires more computation than simply retrieving those rows.

How do you optimize a query?

It’s vital you optimize your queries for minimum impact on database performance.

  1. Define business requirements first. …
  2. SELECT fields instead of using SELECT * …
  3. Avoid SELECT DISTINCT. …
  4. Create joins with INNER JOIN (not WHERE) …
  5. Use WHERE instead of HAVING to define filters. …
  6. Use wildcards at the end of a phrase only.
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Do subqueries improve performance?

The optimizer is more mature for MYSQL for joins than for subqueries, so in many cases a statement that uses a subquery can be executed more efficiently if you rewrite it as join. We cannot modify a table and select from the same table within a subquery in the same SQL statement.

How can I improve my SQL skills?

7 Tips for How to Finally Get Good at (and Master) SQL

  1. Make SQL Part of Your Work Day. …
  2. Document Your SQL Learning Experience. …
  3. Produce Reports using SQL for your business. …
  4. Share Your SQL Knowledge with Others. …
  5. Volunteer or Freelance on an SQL or Database Project. …
  6. Learn SQL Early in Your Career.

Which SQL keyword is used to retrieve a maximum value?

MAX() is the SQL keyword is used to retrieve the maximum value in the selected column.

What makes good SQL code?

Use proper indexes (for faster search results). Always be mindful of NULL occurrences in your data. Always use table aliases when your SQL statement involves more than one source. Improves readability, maintainability and make sure you are fetching the right columns.