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Articles on Trending Technologies
Technical articles with clear explanations and examples
8085 program to alternate D0 bit with specified delay
Now let us see a program of Intel 8085 Microprocessor. In this program we will see how to alternate the D0 bit and send as output.Problem StatementWrite 8085 Assembly language program to alternate D0 bit. And send this as output.DiscussionAlternating D0 bit and sending as output is like generating the square wave. We are adding extra delay in each phase. To generate square wave with 8085, we will rotate 10101010 (AAH) continuously, and send D0 as output. We will mask the accumulator content by 01H. If this is 0, then output will be 0, if it is 1, output will ...
Read MoreDisplay NULL and NOT NULL records except a single specific value in MySQL
To display NULL records, use IS NULL in MySQL. To ignore a single value, use the != operator , which is an alias of the operator.Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, PlayerName varchar(40) ); Query OK, 0 rows affected (0.50 sec)Insert some records in the table using insert command −p>mysql> insert into DemoTable(PlayerName) values('Adam'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(PlayerName) values(NULL); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(PlayerName) values('Sam'); Query OK, 1 row affected (0.13 sec) ...
Read MoreMySQL throws an error when the table name "match" is not surrounded by single quotes?
Do not use single quotes. You need to use backticks around the table name match, since it is a reserved name in MySQL. Following is the error that occurs :mysql> select *from match; 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 near 'match' at line 1Let us first create a table and fix the occurrence of the above error using backticks around the reserved word match, used here as table name −mysql> create table `match` ( Id int NOT ...
Read MoreFix MySQL ERROR 1075 (42000): Incorrect table definition; there can be only one auto column and it must be defined as a key
To fix this error, you need to add PRIMARY KEY to auto_increment field. Let us now see how this error occurs −Here, we are creating a table and it gives the same error −mysql> create table DemoTable ( StudentId int NOT NULL AUTO_INCREMENT, StudentName varchar(40), StudentAge int ); ERROR 1075 (42000) : Incorrect table definition; there can be only one auto column and it must be defined as a keyTo solve the above error, you need to add PRIMARY KEY with AUTO_INCREMENT. Let us first create a table −mysql> create table DemoTable ( StudentId int NOT ...
Read MoreGet Nth weekday of the month from a column with DATE records in MySQL
We need to find the weekday i.e. week 1 from date 1 to 7, week 2 from date 8 to 14, etc. To get the day, use DAY() function in MySQL. Set the conditions to get the weekday (number) using CASE statement.Let us now see an example and create a table −mysql> create table DemoTable ( AdmissionDate date ); Query OK, 0 rows affected (0.63 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('2019-09-12'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values('2019-09-06'); Query OK, 1 row affected (0.16 sec) mysql> ...
Read MoreHow can I select every alternative row and display in descending order in SQL?
To fetch every alternative row, use MOD() under WHERE. Then use ORDER BY DESC to display the result in descending order −select *from yourTableName where mod(yourColumnName, 2)=1 order by yourColumnName DESC;Let us first create a table −mysql> create table DemoTable ( UniqueId int NOT NULL AUTO_INCREMENT PRIMARY KEY, ClientName varchar(40), ClientAge int ); Query OK, 0 rows affected (1.02 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(ClientName, ClientAge) values('Chris', 34); Query OK, 1 row affected (0.47 sec) mysql> insert into DemoTable(ClientName, ClientAge) values('Tom', 45); Query OK, 1 row affected (0.19 sec) mysql> ...
Read MoreSelect all email addresses beginning with 5 numeric characters (regular expression) in MySQL
To get the email addresses beginning with 5 numeric characters, the optional solution is to use REGEXP −select *from yourTableName where yourColumnName regexp "^[0-9]{5}";Let us first create a table −mysql> create table DemoTable ( UserEmailAddress varchar(100) ); Query OK, 0 rows affected (0.76 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('6574John@gmail.com'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('Carol23456@gmail.com'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('98989Chris_45678@gmail.com'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('Mike12@gmail.com'); Query OK, 1 row affected (0.43 ...
Read MoreGet specific value of cell in MySQL
Let us first create a table −mysql> create table DemoTable ( Name varchar(40), Score int ); Query OK, 0 rows affected (0.72 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris Brown', 78); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('John Doe', 88); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('Carol Taylor', 98); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('David Miller', 80); Query OK, 1 row affected (0.68 sec)Display all records from the table using select statement −mysql> select *from ...
Read MoreUsing the value of an alias inside the same MySQL SELECT statement
You cannot directly use an alias in the SELECT. Instead, use a user-defined variable. Following is the syntax. Here, @yourAliasName is our variable and alias −select @yourAliasName :=curdate() as anyAliasName, concat(‘yourValue.', yourColumnName, ' yourValue', @yourAliasName) as anyAliasName from yourTableName;Let us first create a table −mysql> create table DemoTable ( Name varchar(40) ); Query OK, 0 rows affected (0.62 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John Smith'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('Chris Brown'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('David Miller'); ...
Read MoreAdd some value to an int type column value in a table without knowing its current value in SQL?
For this, simply use UPDATE command along with SET. Let us first create a table −mysql> create table DemoTable ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentScore int ); Query OK, 0 rows affected (0.81 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(StudentScore) values(78); Query OK, 1 row affected (0.46 sec) mysql> insert into DemoTable(StudentScore) values(89); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable(StudentScore) values(67); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(StudentScore) values(95); Query OK, 1 row affected (0.25 sec)Display all records from the table ...
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