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How to write the sql statement for mysql to check the number of data items? This problem may be often seen in our daily study or work. I hope you can gain a lot from this question. The following is the reference content that the editor brings to you, let's take a look at it!

In mysql, you can use the COUNT () function to check the number of data rows, and the syntax "SELECT COUNT (*) AS alias FROM data table name;"; the COUNT () function can count the total number of record rows contained in the data table, or return the number of data rows contained in the column based on the query results.

The MySQL COUNT () function counts the total number of record rows contained in the data table, or returns the number of data rows in the column based on the query results, using the following two methods:

COUNT (*) calculates the total number of rows in the table, regardless of whether a column has a numeric value or is null.

COUNT (field name) calculates the total number of rows under the specified column, ignoring rows with null values.

[instance] query the total number of rows in the tb_students_score table. The SQL statement entered and the execution result are shown below.

Mysql > SELECT COUNT (*)-> AS students_number-> FROM tb_students_score;+-+ | students_number | +-+ | 10 | +-+ 1 row in set (0.03 sec)

As you can see from the query results, COUNT (*) returns the total number of rows recorded in the tb_students_score table, regardless of the value. The name of the returned total is students_number.

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