This example uses COUNT(DISTINCT expression) to count non-NULL and distinct values in the column val: SELECT COUNT( DISTINCT val)įROM count_demos Code language: SQL (Structured Query Language) ( sql ) MySQL COUNT() function practical examples Notice that two NULL values are not included in the result. If you specify the val column in the COUNT() function, the COUNT() function will count only rows with non-NULL values in the val column: SELECT COUNT(val)įROM count_demos Code language: SQL (Structured Query Language) ( sql ) WHERE val = 2 Code language: SQL (Structured Query Language) ( sql ) MySQL COUNT(expression) example This example uses the COUNT(*) function with a WHERE clause to specify a condition to count only rows whose value in the column val is 2: SELECT COUNT(*) The following statement uses the COUNT(*) function to return all rows from the count_demos table: SELECT COUNT(*) FROM count_demos Code language: SQL (Structured Query Language) ( sql ) Third, query data from the count_demos table: SELECT * FROM count_demos Code language: SQL (Structured Query Language) ( sql ) MySQL COUNT(*) example Second, insert some rows into the count_demos table: INSERT INTO count_demos(val) ![]() ) Code language: SQL (Structured Query Language) ( sql ) ![]() MySQL COUNT() function illustration Setting up a sample tableįirst, create a table called count_demos: CREATE TABLE count_demos ( The COUNT() function returns 0 if there is no matching row found. The return type of the COUNT() function is BIGINT. ![]() The COUNT(DISTINCT expression) returns the number of distinct rows that do not contain NULL values as the result of the expression. The COUNT(expression) returns the number of rows that do not contain NULL values as the result of the expression. The COUNT(*) returns the number of rows including duplicate, non-NULL and NULL rows. The COUNT(*) function returns the number of rows in a result set returned by a SELECT statement. The COUNT() function has three forms: COUNT(*), COUNT(expression) and COUNT(DISTINCT expression). The COUNT() function allows you to count all rows or only rows that match a specified condition. The COUNT() function is an aggregate function that returns the number of rows in a table. Introduction to the MySQL COUNT() function Offset specify the number of records to skip before starting to return the records db.Limit( 3).Find(&users)ĭb.Limit( 10).Find(&users1).Limit( -1).Summary: in this tutorial, you will learn how to use the MySQL COUNT() function to return the number of rows in a table. Limit specify the max number of records to retrieve SELECT * FROM users ORDER BY FIELD(id,1,2,3) When the destination object has a primary value, the primary key will be used to build the condition, for example: var user = User, If the primary key is a string (for example, like a uuid), the query will be written as follows: db.First(&user, "id = ?", "1b74413f-f3b8-409f-ac47-e8c062e3472a") SELECT * FROM users WHERE id IN (1,2,3) When working with strings, extra care needs to be taken to avoid SQL Injection check out Security section for details. Objects can be retrieved using primary key by using Inline Conditions if the primary key is a number. SELECT * FROM `languages` ORDER BY `languages`.`code` LIMIT 1 no primary key defined, results will be ordered by first field (i.e., `Code`) ![]() works because model is specified using `db.Model()` SELECT * FROM `users` ORDER BY `users`.`id` LIMIT 1 works because destination struct is passed in Additionally, if no primary key is defined for relevant model, then the model will be ordered by the first field. They only work when a pointer to the destination struct is passed to the methods as argument or when the model is specified using db.Model(). The First and Last methods will find the first and last record (respectively) as ordered by primary key. Using Find without a limit for single object db.Find(&user) will query the full table and return only the first object which is not performant and nondeterministic If you want to avoid the ErrRecordNotFound error, you could use Find like db.Limit(1).Find(&user), the Find method accepts both struct and slice data Result.RowsAffected // returns count of records foundĮrrors.Is(result.Error, gorm.ErrRecordNotFound) SELECT * FROM users ORDER BY id DESC LIMIT 1 Get last record, ordered by primary key desc SELECT * FROM users ORDER BY id LIMIT 1 Get the first record ordered by primary key GORM provides First, Take, Last methods to retrieve a single object from the database, it adds LIMIT 1 condition when querying the database, and it will return the error ErrRecordNotFound if no record is found.
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