No, MySQL won’t improve search performance whenever you have leading wildcards because MySQL will be unable to use the index. If you change to ‘anyLetter%’ then it will be able to use indexThe below syntax is better to use with trailing wildcards. The syntax is as follows −SELECT *FROM yourTableName WHERE yoorColumnName LIKE ‘anyLetter%’;The query to create a table is as follows −mysql> create table TrailingWildCardDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name Varchar(20), -> PRIMARY KEY(Id) -> ); Query OK, 0 ... Read More

In PHP, the empty string equals to a NULL value, but in MySQL, the case is the different i.e. empty string is not equal to NULL value. To understand the above syntax, let us create a column with NOT NULL constraint while you can insert an empty string.Let us create a table. The query to create a table is as follows −mysql> create table EmptyStringNotNullDemo    -> (    -> Id int NOT NULL AUTO_INCREMENT,    -> Name varchar(10) not null,    -> PRIMARY KEY(Id)    -> ); Query OK, 0 rows affected (0.83 sec)Now you can insert some records ... Read More

To create column names to be used in a query, you need to use a user-defined variable with the set command. The syntax is as follows −SET @anyVariableName := (    SELECT CONCAT    (       "SELECT",    GROUP_CONCAT(CONCAT(" 1 as ", COLUMN_NAME) SEPARATOR ', '), " FROM DUAL")    FROM INFORMATION_SCHEMA_COLUMNS    WHERE TABLE_NAME= ‘yourTableName’ );Now prepare the statement using the PREPARE command. The syntax is as follows −PREPARE anyVariableName from @anyVariableName;Execute statement using EXECUTE command. The syntax is as follows −EXECUTE anyVariableName;Deallocate the prepared statement using DEALLOCATE command. The syntax is as follows −DEALLOCATE PREPARE anyVariableName; ... Read More

To get the column name on the result set, you need to use getMetaData() method. The prototype of getMetadata() is as follows −ResultSetMetaData getMetaData throws SQLException;Create a MySQL table with 5 column names. The query to create a table is as follows −mysql> create table javagetallcolumnnames    -> (    -> Id int NOT NULL AUTO_INCREMENT,    -> Name varchar(20),    -> Age int,    -> Salary float,    -> Address varchar(100),    -> PRIMARY KEY(Id)    -> ); Query OK, 0 rows affected (1.34 sec)The following is the Java code that gets the column name on ResultSet. The code ... Read More

If your cast does not work, then you can use yourColumnName*1 with ORDER BY clause.Using yourColumnName*1. The syntax is as follows:SELECT yourColumnName1, yourColumnName2, ...N FROM yourTableName ORDER BY yourColumnName*1 DESC;You can also use CAST() operator. The syntax is as follows:SELECT yourColumnName1, yourColumnName2, ...N FROM yourTableName ORDER BY CAST(yourColumnName as DECIMAL(8, 2)) DESC;To understand the above syntax, let us create a table. The query to create a table is as follows:mysql> create table VarcharColumnAsFloatDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Amount varchar(20), -> PRIMARY KEY(Id) ... Read More

To find rows and update with new value where column value ends with specific substring you need to use LIKE operator.The syntax is as follows:UPDATE yourTableName SET yourColumnName=’yourValue’ WHERE yourColumnName LIKE ‘%.yourString’;To understand the above syntax, let us create a table. The query to create a table is as follows:mysql> create table RowEndsWithSpecificString -> ( -> Id int NOT NULL AUTO_INCREMENT, -> FileName varchar(30), -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (1.50 sec)Now you can insert some records in the table using ... Read More

To fetch rows where first character is not alphanumeric, you can use the following regular expression.Case 1 − If you want those rows that starts from a digit, you can use the following syntax −SELECT *FROM yourTableName WHERE yourColumnName REGEXP '^[0-9]';Case 2 − If you want those rows that start from an alphanumeric, use the following syntax −SELECT *FROM yourTableName WHERE yourColumnName REGEXP '^[^0-9A-Za-z]' ;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table getRowsFirstNotAlphanumeric -> ( -> Id int NOT NULL AUTO_INCREMENT, -> UserPassword varchar(20), -> PRIMARY ... Read More

If you want to get only digits using REGEXP, use the following regular expression( ^[0-9]*$) in where clause.Case 1 − If you want only those rows which have exactly 10 digits and all must be only digit, use the below regular expression.SELECT *FROM yourTableName WHERE yourColumnName REGEXP '^[0-9]{10}$';Case 2 − If you want only those rows with the digit either 1 or more, the following is the syntax −SELECT *FROM yourTableName WHERE yourColumnName REGEXP '^[0-9]*$';The above syntax will give only those rows that do not have any any characters.To understand the above syntax, let us create a table. The query ... Read More

Order by date and set the empty dates in the last with the help of ORDER BY clause and IS NULL property. The syntax is as follows:SELECT *FROM yourTableName ORDER BY (yourDateColumnName IS NULL), yourDateColumnName DESC;In the above syntax, we will sort the NULL first after that date. To understand the above syntax, let us create a table. The query to create a table is as follows:mysql> create table DateColumnWithNullDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> LoginDateTime datetime, -> PRIMARY KEY(Id) -> ... Read More

The function TIME_TO_SEC() can be used in MySQL. If you want to convert datetime to seconds use the strtotime() from PHP. The MySQL syntax is as follows:SELECT TIME_TO_SEC(ABS(timediff(‘yourDateTimeValue’, now())));Now you can convert PHP datetime to seconds with the help of strtotime().First, you need to install XAMPP server to run your PHP program.After installing XAMPP successfully in C drive, here is the location wherein you need to include the PHP file. The snapshot is as follows:Note: Here, I have changed port of Apache to 8086 because default port was held by another program. This is done to begin running PHP program.Therefore, ... Read More