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MySQLi Articles
Page 197 of 341
How can I create a MySQL boolean column and assign value 1 while altering the same column?
To assign value 1 while altering, use the MySQL DEFAULT. This will itself enter 1 if nothing is inserted in the same column while using the INSERT command.Let us first create a table −mysql> create table DemoTable ( isAdult int ); Query OK, 0 rows affected (1.39 sec)Following is how you can assign value 1 default to the already created column −mysql> alter table DemoTable CHANGE isAdult isAdult BOOLEAN DEFAULT '1' NOT NULL; Query OK, 0 rows affected (1.18 sec) Records: 0 Duplicates: 0 Warnings: 0Insert some records in the table using insert command −mysql> insert into DemoTable values(); ...
Read MoreMySQL query to find the number of rows in the last query
For this, use the FOUND_ROWS in MySQL. Following is the syntax −SELECT SQL_CALC_FOUND_ROWS TABLE_NAME FROM `information_schema`.tables WHERE TABLE_NAME LIKE "yourValue%" LIMIT yourLimitValue;Here, I am using the database ‘web’ and I have lots of tables, let’s say which begins from DemoTable29. Let us implement the above syntax to fetch only 4 of such rows −mysql> SELECT SQL_CALC_FOUND_ROWS TABLE_NAME FROM `information_schema`.tables WHERE TABLE_NAME LIKE "DemoTable29%" LIMIT 4;This will produce the following output −+--------------+ | TABLE_NAME | +--------------+ | demotable29 | | demotable290 | | demotable291 | | demotable292 | +--------------+ 4 rows in set (0.01 sec)Here is the query ...
Read MoreGet only the date from datetime in MySQL?
To get only the date from DateTime, use the date format specifiers −%d for day %m for month %Y for yearLet us first create a table −mysql> create table DemoTable ( AdmissionDate datetime ); Query OK, 0 rows affected (0.52 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('2019-07-21 12:34:56'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('2016-08-18 10:00:02'); Query OK, 1 row affected (0.51 sec) mysql> insert into DemoTable values('2018-01-03 11:02:20'); Query OK, 1 row affected (0.12 sec)Display all records from the table using select statement −mysql> select *from ...
Read MoreReplace only a specific value from a column in MySQL
To replace, use the REPLACE() MySQL function. Since you need to update the table for this, use the UPDATE() function with the SET clause.Following is the syntax −update yourTableName set yourColumnName=replace(yourColumnName, yourOldValue, yourNewValue);Let us first create a table −mysql> create table DemoTable ( FirstName varchar(100), CountryName varchar(100) ); Query OK, 0 rows affected (0.69 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John', 'AUS'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('Bob', 'AUS'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('Chris', 'US'); Query OK, 1 ...
Read MoreMySQL query to place a specific record on the top
For this, you can use the ORDER BY CASE statement. Let us first create a table −mysql> create table DemoTable ( StudentName varchar(100), StudentMarks int ); Query OK, 0 rows affected (0.97 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris', 45); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('John', 67); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('David', 89); Query OK, 1 row affected (0.46 sec) mysql> insert into DemoTable values('John', 98); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('Mike', ...
Read MoreMySQL query to order by the first number in a set of numbers?
To order by the first number in a set of numbers, use ORDER BY SUBSTRING_INDEX(). Let us first create a table −mysql> create table DemoTable ( SetOfNumbers text ); Query OK, 0 rows affected (0.53 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('245, 654, 76, 89, 98'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('2000, 567, 9090, 6789'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('1001, 90595, 657, 99'); Query OK, 1 row affected (0.20 sec)Display all records from the table using select statement −mysql> ...
Read MoreCan we use reserved word ‘index’ as MySQL column name?
Yes, but you need to add a backtick symbol to the reserved word (index) to avoid error while using it as a column name.Let us first create a table −mysql> create table DemoTable ( `index` int ); Query OK, 0 rows affected (0.48 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(1000); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values(1020); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(967); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(567); Query OK, 1 row affected (0.12 ...
Read MoreGetting maximum from a column value and set it for all other values in the same column with MySQL?
Let us first create a table −mysql> create table DemoTable ( FirstName varchar(100), Score int ); Query OK, 0 rows affected (0.60 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('David', 59); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('Chris', 97); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable values('Bob', 98); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Carol', 91); Query OK, 1 row affected (0.11 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the ...
Read MoreCompare for NULL value and display value 1 for these values in a new MySQL column?
For this, use IF() along with IS NULL property. Let us first create a table −mysql> create table DemoTable ( Name varchar(100), CountryName varchar(100) ); Query OK, 0 rows affected (0.70 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris', 'US'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Mike', NULL); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(Name) values('David'); Query OK, 1 row affected (0.38 sec) mysql> insert into DemoTable values('Bob', 'AUS'); Query OK, 1 row affected (0.45 sec)Display all records from the table using select ...
Read MoreHow to find specific row with a MySQL query?
Let us first create a table −mysql> create table DemoTable ( UserId int, UserName varchar(100) ); Query OK, 0 rows affected (0.66 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(100, 'Chris'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values(101, 'Bob'); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable values(102, 'David'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(103, 'Mike'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(104, 'Sam'); Query OK, 1 row affected (0.16 sec)Display all records ...
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