learn mysql workbench

Tags: style blog io ar color os SP data onLearn Nodejs connect to MySQL database:1. Install MySQL Database First　　NPM install MySQL2. Test the Connection database:var sql = require ("MySQL"); var db = Sql.createconnection ({host: "localhost", ure: "Root", Password: "", Database: "Test"});d B.query ( "SELECT * from user where 1",function(err,data) { if(err)

requires a locator. Examples of use are shown below: select * from student where name regexp ‘^\\.‘;//检查字符串是否以点开始。 Note: ^ There are two ways to use this: In the collection (defined with [and]), it is used to negate the collection, for example [^01234]: refers to the match except for 012345 other characters. Used to refer to the beginning of a string. SummaryThe above introduction of things more, I believe suddenly also more difficult to master good, but, remi

folder3.2. Configuring solrconfig.xml3.2.1, referencing related librariesThe solrconfig.xml includes most of the parameters used to configure the behavior of itself, which is scoped to the current core. Location in the Files folder the file is located under {%solr_home%} example\solr\collection1\conf.The data import needs to reference the MySQL driver package and the package required by the DataImport.Include in the file such as the following:3.2.2,

=118.1964111328SET @wd =39.5591182422Value updates, analysis gets the range of attractions information5. Questions:If you take a series of expressions directly in where, this will result in the inability to use the spatial index:650) this.width=650; "Src=" Https://s2.51cto.com/oss/201711/11/2fa268136801e296920360f50ace6d02.png-wh_500x0-wm_3 -wmp_4-s_2852158178.png "title=" A11.png "alt=" 2fa268136801e296920360f50ace6d02.png-wh_ "/>Workaround:1, the Where after the expression is processed into a

Tags: oat namespace mysql type tin sign approximate dataEstablishment of the table of norms1. The expression is the concept of the field, must be named using IS_XXX, the data type is unsigned tinyint (1 means yes, 0 means no).2. Table names do not use plural nouns.3. Disable reserved words.4. Decimal type, the use of float and double is forbidden.5. The name of the table is best added to the "Business noun _ table role".6. Update Field comments when m

condition --change age of ID 11 to 35,sex to M valueUpdate Stu set age=35,sex= ' m ' where id=11;Query OK, 1 row affected (0.16 sec)Rows matched:1 changed:1 warnings:0 --Change the data value for ID values 12 and 14 to M,classid to lamp92Update Stu set sex= ' m ', classid= ' lamp92 ' where ID in (12,14);Query OK, 2 rows affected (0.09 sec)Rows matched:2 Changed:2 warnings:0Delete data Format: Delete from table name [where condition] --delete data in the Stu table with an ID value of 100Delete f

Learn MySQL with teacher Wang: aggregate functionsTeacher: Wang Shaohua QQ Group No.: 483773664 Learning Content Usage of COUNT (), SUM (), AVG (), MAX (), and Min () four aggregate functionsThe aggregate functions include count (), SUM (), AVG (), MAX (), and Min ().One, COUNT ()(a) IntroductionThe count () function is used to count the number of records.(ii) examplesUse the count () function to count the

)3.4FOREIGN key (foreign key)------used to mark a row of this table in another table or this table3.5CHECK------Ensure that a column of data meets a particular condition3.6The default------sets an initial value that is set to this value when the data is not assigned3.7INDEX------used to quickly create and retrieve data from a database4. This is a constraint summary, I'll try these constraints later, (not full,unique,primary key has been tried in the blog that added the primary key)(attached)

() limit0,1),1,1))> the# Show Presence1’ and ASCII(Substr (Selecttable_name fromInformation_schema.tableswhereTable_schema=Database() limit0,1),1,1))122# Show Presence1’ and ASCII(Substr (Selecttable_name fromInformation_schema.tableswhereTable_schema=Database() limit0,1),1,1))109# Show Presence1’ and ASCII(Substr (Selecttable_name fromInformation_schema.tableswhereTable_schema=Database() limit0,1),1,1))103# Display does not exist1’ and ASCII(Substr (Selecttable_name fromInformation_schema.table

DELETE tbl_name [. *] [, tbl_name[.*]] ...From Table_references[WHERE Where_condition]Now you want to delete the duplicate records and keep the records with the smaller ID numbers.A table simulates multiple table deletions to achieve:(1) Finding duplicate records(2) Refer to this table to delete the data from the table above"Involves subqueries, joins, multiple table updates, multiple table deletions, implements its own connection when multiple table operations are made, and deletes duplicate re

MySQL must knowFirst, there's a table.Customer table: Product table:Order Element table: Product record table:Order Form:Seller Table:16th. Creating an advanced junctionSelect concat (rtrim(vend_name),'(',RTrim(vend_country), ' )'as fromorder by Vend_name;There are two benefits of using aliases:1. Shorten the SQL statement2. Allow the same table to be used multiple times in a single SELECT statementUse different types of junctions1. Self-couplingConne

To display the database:SHOW DATABASES database_name;To create a database:CREATE DATABASES database_name;To delete a database:DROP DATABASE database_name;To create a data table:CREATE table(Field name 1, data type [column-level constraint] [default],);Cases:CREATE TABLE TB1(ID INT (11),NAME VARCHAR (20));Primary key: Field name data type PRIMARY key[default value];Cases:CREATE TABLE TB1(ID INT (one) PRIMARY KEY,NAME VARCHAR (20));Or:CREATE TABLE TB1(ID INT (11),NAME VARCHAR (20)PRIMARY KEY (ID))

actually used.Note: in subqueries. Column must matchUsing subqueries as calculated fieldsAll of the above describes using subqueries as conditions. The following describes the use of subqueries as calculated fields.Or a sample to illustrate.If you need to display the total number of orders for each customer in the Customers table.To run this operation, the process is as follows: Retrieving a list of customers from the Customers table For each customer that is retrieved. Coun

Log in to MySQL databaseMysql-u root-pDisplay (query) all databasesshow databases;Enter the databaseUse Dataname;Create a databaseCreate Database Dataname;/* DML: They are select, UPDATE, INSERT, DELETE, just like its name, these 4 commands are the language used to manipulate the data in the database */Query table for all content of personselect * from person;Insert a piece of dataInsert into person (name,age) value (' Zhagnsan ', 23);Add Name to ID 1