mysql

问题 I have a question to ask. Firstly, I have a table, where the parent has parent_id is 0 and the child has parent_id equal parent id. parent_id of all children are stored as a json encoded array (one child record can have many parents). So, how can I get all the children of the parent when I pass one parent id. I tried but it won't work and I don't have a clue. Here's the code: function get_child_product($parent_id, $limit, $start) { $this -> db -> from('product'); $this -> db -> where(json

问题 I have a question to ask. Firstly, I have a table, where the parent has parent_id is 0 and the child has parent_id equal parent id. parent_id of all children are stored as a json encoded array (one child record can have many parents). So, how can I get all the children of the parent when I pass one parent id. I tried but it won't work and I don't have a clue. Here's the code: function get_child_product($parent_id, $limit, $start) { $this -> db -> from('product'); $this -> db -> where(json

问题 I have a question to ask. Firstly, I have a table, where the parent has parent_id is 0 and the child has parent_id equal parent id. parent_id of all children are stored as a json encoded array (one child record can have many parents). So, how can I get all the children of the parent when I pass one parent id. I tried but it won't work and I don't have a clue. Here's the code: function get_child_product($parent_id, $limit, $start) { $this -> db -> from('product'); $this -> db -> where(json

问题 I have four models: articles , authors and tags . Each article can have many authors, and also can have many tags. So my DB will have the following tables: `article` `article_author` `author` `article_tag` `tags` Here in MySQL: DROP TABLE IF EXISTS article_tag; DROP TABLE IF EXISTS article_author; DROP TABLE IF EXISTS author; DROP TABLE IF EXISTS tag; DROP TABLE IF EXISTS article; CREATE TABLE IF NOT EXISTS author ( id INT(11) NOT NULL AUTO_INCREMENT, name VARCHAR(255), PRIMARY KEY (id) );

问题 I have four models: articles , authors and tags . Each article can have many authors, and also can have many tags. So my DB will have the following tables: `article` `article_author` `author` `article_tag` `tags` Here in MySQL: DROP TABLE IF EXISTS article_tag; DROP TABLE IF EXISTS article_author; DROP TABLE IF EXISTS author; DROP TABLE IF EXISTS tag; DROP TABLE IF EXISTS article; CREATE TABLE IF NOT EXISTS author ( id INT(11) NOT NULL AUTO_INCREMENT, name VARCHAR(255), PRIMARY KEY (id) );

问题 I have four models: articles , authors and tags . Each article can have many authors, and also can have many tags. So my DB will have the following tables: `article` `article_author` `author` `article_tag` `tags` Here in MySQL: DROP TABLE IF EXISTS article_tag; DROP TABLE IF EXISTS article_author; DROP TABLE IF EXISTS author; DROP TABLE IF EXISTS tag; DROP TABLE IF EXISTS article; CREATE TABLE IF NOT EXISTS author ( id INT(11) NOT NULL AUTO_INCREMENT, name VARCHAR(255), PRIMARY KEY (id) );

问题 I would like to pull values from a PHP array at random, without pulling the same value twice before I've pulled all values from the entire array. In other words, if I have the array... _____ | foo | | bar | | baz | |_____| ...I want to pull a random value three times without pulling the same value twice, so I could have... 1st: foo foo bar bar baz baz 2nd: bar baz foo baz foo bar 3rd: baz bar baz foo bar foo ...on my three separate pulls. Now, I realize I could do this by simply removing the

问题 I have succesfully created a database in mySQL using the commandline and imported some data. It currently looks like this.. desc data; +----------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------+-------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | code | varchar(10) | YES | | NULL | | +----------+-------------+------+-----+---------+----------------+ SELECT * FROM data; +

问题 I am working in a PHP + MySQL application. The application is working fine for me. But when I hosted it in another server, I got a MySQL error: Error Code: 1364. Field 'field' doesn't have a default value I know this is a problem with the MySQL version and we should setup default values for all columns. But currently I have more than 100 tables. So I need to set default value to NULL for all columns in all tables that has no default value yet. I can't make use of the strict mode option,

问题 So I'm using the MySql.Data package for my .NET Core project and store password hashes and salts (of type byte[] ) as varbinary() to the database. When selecting the password hash and salt from a user I need a way to convert the result back to a byte array. Given this sample code Stream passwordHashStream = dbDataReader.GetStream(0); byte[] passwordHash; using (MemoryStream memoryStream = new MemoryStream()) { await passwordHashStream.CopyToAsync(memoryStream); passwordHash = memoryStream