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Articles by Sharon Christine
Page 33 of 34
MySQL queries to update date records with NULL values
You can use IFNULL() for this. Let us first create a table −mysql> create table DemoTable -> ( -> added_date date, -> updated_date date -> ); Query OK, 0 rows affected (0.95 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('2019-01-10', '2019-06-01'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('2019-05-19', NULL); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(NULL, '2019-09-05'); Query OK, 1 row affected (0.18 sec)Display all records from the table using ...
Read MoreRetrieving MySQL Database structure information from Java?
Use DatabaseMetaData class to retrieve MySQL database structure. In this example, we will display all the table names of database “web” using Java with the help of getMetaData().Following is the Java code −Exampleimport java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; import com.mysql.jdbc.DatabaseMetaData; public class getDatabaseInformationDemo { public static void main(String[] args) { Connection con = null; try { con = DriverManager.getConnection("jdbc:mysql://localhost:3306/web?useSSL=false", "root", "123456"); DatabaseMetaData information = (DatabaseMetaData) con.getMetaData(); String allTableName[] = { "TABLE" ...
Read MoreAdd a new column and index to an existing table with ALTER in a single MySQL query?
To add a new column to an existing table, use ADD. With that, to add a new index, use the ADD INDEX(). Let us first create a table −mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(100), -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.69 sec)Let us check the description of the table −mysql> desc DemoTable;This will produce the following output −+-------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------+--------------+------+-----+---------+----------------+ | Id ...
Read MoreHow to find a value between range in MySQL?
For this, use BETWEEN operator in MySQL. Let us first create a table −mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Start int, -> End int -> ); Query OK, 0 rows affected (0.91 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Start, End) values(100, 200); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(Start, End) values(400, 500); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(Start, End) values(210, 350); Query OK, 1 row affected (0.11 sec)Display all ...
Read MoreWhy does MySQL evaluate "TRUE or TRUE and FALSE" to true?
MySQL evaluates “TRUE or TRUE and FALSE” to true because AND has the highest priority than OR i.e. AND is evaluated before OR.The MySQL evaluates the above statement like this. The AND operator gets evaluated first −(TRUE or (TRUE AND FALSE))The statement (TRUE AND FALSE) gives the result FALSE. Then the second statement evaluates like this −(TRUE or FALSE)The above statement gives the result TRUE.Let us implement one by one −mysql> select (TRUE AND FALSE); +------------------+ | (TRUE AND FALSE) | +------------------+ | 0 | ...
Read MoreGet the count of duplicate values from a single column in MySQL?
Let us first create a table −mysql> create table DemoTable -> ( -> Number int -> ); Query OK, 0 rows affected (0.83 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(20); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable values(20); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(10); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable values(30); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(10); Query OK, ...
Read MoreCan we use IN() to search between comma separated values within one field?
Instead of IN(), use FIND_IN_SET to search between comma separated values within one field. Let us first create a table −mysql> create table DemoTable -> ( -> ListOfValues text -> ); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('10|20|30|40|50|60|100'); Query OK, 1 row affected (0.18 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output −+-----------------------+ | ListOfValues | +-----------------------+ | 10|20|30|40|50|60|100 ...
Read MoreFinding the minimum and maximum value from a string with numbers separated by hyphen in MySQL?
Use MIN() function along with SUBSTRING() for minimum, whereas MAX() for maximum. Let us first create a table −mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Value varchar(100) -> ); Query OK, 0 rows affected (0.76 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Value) values('10-20'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable(Value) values('200-100'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(Value) values('780-235'); Query OK, 1 row affected ...
Read MoreCan we implement 'LIKE' and 'IN' in a single MySQL query?
For more efficiency, use Regular Expression for the same task. Let us first create a table −mysql> create table DemoTable -> ( -> Name varchar(30) -> ); Query OK, 0 rows affected (0.62 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('Chris'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Robert'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('David'); Query OK, 1 row affected ...
Read MoreWhat are Java methods equivalent to C# virtual functions?
All instance methods in Java are virtual except, static methods and private methods.
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