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Articles on Trending Technologies
Technical articles with clear explanations and examples
What is the benefit of zerofill in MySQL?
ZEROFILL pads the displayed value of the field with zeros up to the display width set in the column definition. Let us understand the role of zero fill in MySQL using an example. Creating a table with two columns, one has zerofill and the second one does not. The query to create a table. mysql> create table ZeroFillDemo -> ( -> First int(18) zerofill, -> Second int(18) -> ); Query OK, 0 rows affected (0.63 sec) We can insert records in the table with the help ...
Read MoreHow to debug Lock wait timeout exceeded on MySQL?
The debug Lock wait timeout situation occurs because of some threads. If one thread is holding on to some records for a very long time, it means the thread has exceeded time. To see all the details, implement the following query − mysql> SHOW ENGINE INNODB STATUS; The following is the output. +--------+------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Type | Name | Status ...
Read MoreHow to get the size of the tables of a MySQL database?
To get the size of the tables of a MySQL database, you can use the “information_schema.tables”. Here is the syntax to know the size of all tables. SELECT TABLE_NAME AS `ALLTABLESNAME`, ROUND((DATA_LENGTH + INDEX_LENGTH) / 1024 / 1024) AS `TABLESIZEIN(MB)` FROM information_schema.TABLES WHERE TABLE_SCHEMA = "yourDatabaseName" ORDER BY (DATA_LENGTH + INDEX_LENGTH) ASC; Let us apply the above syntax to get the size of the tables. mysql> SELECT TABLE_NAME AS `ALLTABLESNAME`, ROUND((DATA_LENGTH + INDEX_LENGTH) / 1024 / 1024) AS `TABLESIZEIN(MB)` -> FROM information_schema.TABLES WHERE TABLE_SCHEMA = "business" ...
Read MoreWhy doesn't MySQL support millisecond / microsecond precision?
The millisecond/ microsecond precision wasn’t supported in previous versions like 5.6.4. But now MySQL supports millisecond/ microsecond precision with timestamp, datetime, and time. The official statement. “MySQL now supports fractional seconds for TIME, DATETIME, and TIMESTAMP values, with up to microsecond precision”. You can check the MySQL version on your system using the version() method. mysql> SELECT version(); The following is the output. +-----------+ | version() | +-----------+ | 8.0.12 | +-----------+ 1 row in set (0.01 sec) Let us now see the syntax to check the date difference. mysql> SELECT DATEDIFF(now(), ...
Read MoreInstruction type MVI M, d8 in 8085 Microprocessor
In 8085 Instruction set, this instruction MVI M, d8 is used to load a memory location pointed by HL pair with an 8-bit value directly. This instruction uses immediate addressing for specifying the data. It occupies 2-Bytes in memory. Mnemonics, Operand Opcode(in HEX) Bytes MVI M, Data 36 2 As an example, we can consider MVI M, ABH as an example instruction of this type. It is a 2-Byte instruction, with opcode for MVI M using up one Byte, and ABH using up another more Byte. We are considering that HL register pair is ...
Read MoreInstruction type LDA a16 in 8085 Microprocessor
In 8085 Instruction set, LDA is a mnemonic that stands for LoaD Accumulator with the contents from memory. In this instructionAccumulatorwill get initialized with 8-bit content from the 16-bit memory address as indicated in the instruction as a16. This instruction uses absolute addressing for specifying the data. It occupies 3-Bytes in the memory. First Byte specifies the opcode, and the successive 2-Bytes provide the 16-bit address, i.e. 1-Byte each for each memory location. Mnemonics, Operand Opcode(in HEX) Bytes LDA Address 3A 3 Let us consider LDA 4050H as an example instruction of this type. ...
Read MoreLayered Operating System
The operating system is split into various layers In the layered operating system and each of the layers have different functionalities. This type of operating system was created as an improvement over the early monolithic systems. Why Layering in Operating System? Layering provides a distinct advantage in an operating system. All the layers can be defined separately and interact with each other as required. Also, it is easier to create, maintain and update the system if it is done in the form of layers. Change in one layer specification does not affect the rest of the layers. Each of ...
Read MoreHow do I kill all the processes in MySQL “show processlist”?
We can kill the processes with the help of the ‘kill’ command. However, you need to kill those processes one by one, since MySQL does not have any massive kill command. To check how many processes exist, use ‘show processlist’ mysql> show processlist; The following is the output. +----+-----------------+-----------------+------+---------+------+------------------------+------------------+ | Id | User | Host | db | Command | Time | State ...
Read MoreInstruction type STA a16 in 8085 Microprocessor
In 8085 Instruction set, STA is a mnemonic that stands for STore Accumulator contents in memory. In this instruction, Accumulator8-bit content will be stored to a memory location whose 16-bit address is indicated in the instruction as a16. This instruction uses absolute addressing for specifying the destination. This instruction occupies 3-Bytes of memory. First Byte is required for the opcode, and next successive 2-Bytes provide the 16-bit address divided into 8-bits each consecutively. Mnemonics, Operand Opcode(in HEX) Bytes STA Address 32 3 Let us consider STA 4050H as an example instruction of this type. ...
Read MoreHow to save MySQL query output to excel or .txt file?
To save MySQL query output into a text file, we can use the OUTFILE command. Let us first create a table. mysql> create table SaveintoTextFile -> ( -> id int, -> name varchar(100) -> ); Query OK, 0 rows affected (0.55 sec) Inserting records into the table. mysql> insert into SaveintoTextFile values(1, 'John'); Query OK, 1 row affected (0.44 sec) mysql> insert into SaveintoTextFile values(101, 'Carol'); Query OK, 1 row affected (0.17 sec) mysql> insert into SaveintoTextFile values(3, 'David'); Query OK, 1 row ...
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