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MySQLi Articles
Page 327 of 341
MySQL- GROUP and COUNT by date?
You can use GROUP BY clause and COUNT() function for this. The syntax is as follows −SELECT yourColumnName1, yourColumnName2, ..N, COUNT(*) as anyAliasName FROM yourTableName GROUP BY yourColumnName1, yourColumnName2;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table GroupAndCountByDate -> ( -> Id int NOT NULL AUTO_INCREMENT, -> TripDate date, -> ShopId int, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.79 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> ...
Read MoreReturn order of MySQL SHOW COLUMNS?
To return order of MySQL SHOW COLUMNS, you need to use ORDER BY clause. The syntax is as follows −SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE table_name = ‘yourTableName’ AND column_name LIKE 'yourStartColumnName%' ORDER BY column_name DESC;Let us create a table in database TEST. The query to create a table is as follows −mysql> create table OrderByColumnName -> ( -> StudentId int, -> StudentFirstName varchar(10), -> StudentLastName varchar(10), -> StudentAddress varchar(20), -> StudentAge int, -> StudentMarks int ...
Read MoreMySQL Query to get count of unique values?
To count the unique values on a column, you need to use keyword DISTINCT. To understand how it is done, let us create a table. The query to create a table is as follows −mysql> create table UniqueCountByIPAddress -> ( -> Id int NOT NULL AUTO_INCREMENT, -> UserHits int, -> UserIPAddress varchar(50), -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.69 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into UniqueCountByIPAddress(UserHits, UserIPAddress) values(10, '127.0.0.1'); Query OK, 1 row affected (0.20 sec) mysql> insert into ...
Read MoreShould I store a field PRICE as an int or as a float in the database?
You do not need to store a field PRICE as an int or as float in the database. For this, you can set the DECIMAL()..Most of the time integers can be used to represent the float point numbers and these integers are internally cast into DECIMAL() data type. Therefore, if you have field PRICE then always use DECIMAL() data type. The syntax is as follows −DECIMAL(M, D);Here, M represents the ‘TotalNumberOfDigit’ and D represents the ‘Number OfDigitAfterDecimalPoint’.To understand the above concept, let us create a table with field PRICE as DECIMAL data type. The query is as follows −mysql> create ...
Read MoreMySQL how to declare a datetime variable?
To declare a datetime variable, you need to use a user-defined variable using the SET command. The syntax is as follows −SET @anyVariableName=’yourdatetimeValue’;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table datetimeVariables -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(10), -> ArrivalDatetime datetime, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.78 sec)Insert some records in the table using insert command. The query to ...
Read MoreUsing LIKE for two where clauses in MySQL?
You don’t need to use two where clauses. Use two conditions using the LIKE operator and AND operator.To understand how to use LIKE for this, let us create a table. The query to create a table is as follows −mysql> create table WhereDemo -> ( -> Id int, -> Name varchar(20) -> ); Query OK, 0 rows affected (0.56 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into WhereDemo values(101, 'Maxwell'); Query OK, 1 row affected (0.14 sec) mysql> insert into WhereDemo values(110, 'David'); Query ...
Read MoreResolve usage of quotes ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use?
In MySQL, you can use two different types of quotation marks which is backtick and another is single quotes or double quotes. In this case, maybe you are using single quotes to the column name that’s why you are getting error. You need to use the backtick symbol (` `) instead of single quotes. Backtick can be used with column names while single quotes can be used for strings.To understand the above error, let us create a table. The query to create a table is as follows −mysql> create table Backtick_SymbolDemo -> ( -> Id int NOT NULL ...
Read MoreFind a list of invalid email address from a table in MySQL?
To find invalid email address, use the below syntax −SELECT yourColumnName FROM yourTableName WHERE yourColumnName NOT LIKE '%_@_%._%';The above syntax will give the list of all invalid email addresses. To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table FindInvalidEmailAddressDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(20), -> EmailAddress varchar(40), -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.75 sec)Now you can insert some records in the table using insert command. We have inserted some invalid ...
Read MoreMySQL "not a variable or NEW pseudo-variable" message. What is this error in my Stored Procedure?
To get rid of this error message, let us see a sample example. But before that let us go through the concept to fix it.Use variable to get the value from stored procedure. The variable will prefix with @ symbol. The syntax is as follows −CALL yourStoredProcedureName(yourParameter1, yourParameter2, ..........N, @yourVariableName);To see the value of variable you need to use select statement. The syntax is as follows −SELECT @yourVariableName;To understand the above syntax, let us create a table and insert some records in the table.The query to create a table is as follows −mysql> create table StoredProcedureDemo -> ( ...
Read MoreGet the type of a variable in MySQL?
You cannot get the type of variable in MySQL. Cast the type of variable into another using CAST operator. The syntax is as follows −SET @yourVariableName:=’anyValue’Use the CAST operator to cast to another type. The syntax is as follows −SELECT CAST( @yourVariableName AS SIGNED);To understand the above syntax, let us cast to another type.Case 1: String to unsigned −mysql> set @StringToInt:='12345'; Query OK, 0 rows affected (0.00 sec)The query is as follows to another type −mysql> select CAST(@StringToInt as UNSIGNED);The following is the output −+--------------------------------+ | CAST(@StringToInt as UNSIGNED) | +--------------------------------+ | 12345 ...
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