Typically, MySQL database developers need to check if a specific value exists in a database column or not. But sometimes you may need to check if an entire row exists in MySQL. In this article, we will learn how to do this.
How to Check if Row Exists in MySQL
Let us say you want to check if a specific row exists in table named data. There are several simple ways to check if a row exists or not in MySQL table.
1. Using SELECT EXISTS
You can do so using the following query.
SELECT EXISTS(SELECT * FROM table_name WHERE ...)
For example, if you want to check if a row with id=5 exists in table named data, you can do so using the following query.
SELECT EXISTS(SELECT * FROM data WHERE id=5)
Generally, a SELECT query begins with a column list but when you use SELECT EXISTS, you do not need to specify a column list or a table name for that matter.
The above query returns 1 if the row exists, else it returns 0.
2. Using Count(*)
There are also several other ways to check if a row exists. Here is another way using count(*) where we return the number of rows that meets our requirement.
select count(*) from table_name where ...
The above query does not give a direct 1 or 0 depending on whether the row exists or not. It just returns the total number of rows.
3. Using LIMIT 1
You can also use LIMIT 1 clause to check if the row exists, as shown below.
select * from table_name where ... LIMIT 1
In this case, MySQL returns the first matching row instead of a Boolean 1 or 0 to indicate the presence of row. If the row does not exist, it returns null.
In this article, we have learnt how to easily check if row exists in MySQL. Of all the methods mentioned above, using SELECT EXISTS is the fastest, in most cases.
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