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permission list on database name. Table name to user name @localhost identified by ' password '2.8.1 Permissions ListInsert: AddDelete: RemoveUpdate: ModifySelect: QueryGrant SELECT on nsd.* to [email protected] identified by ' 456 ' #lisi用户在本地登录后拥有对nsd库的所有表的查询权限Select User,password from Mysql.user where user= ' Lisi ';2.9 Modification of the database 2.9.1 Insert base values (6, ' Barbara ', 123456);Add a
Source: https://www.scarydba.com/2017/06/20/database-fundamentals-3-whats-database/Grant FritcheyTranslation: Shesheni Liu Jongmao Xu Yali Lai HuifangPresidentIt is important to note that many people do not need to create their own databases. You may also not create your own tables or other data structures. You may also need to run backups, re-store and secure th
file, and in this window select the database file (suffix) you want to attach . MDF) 4. Click " OK " button to complete the installation of additional database files, click the OK button to complete the database additional tasks. Statement: 1. Change the name of the database 2. Add columns, delete columns if ther
Tags: mdf Create one of the files www. Secure Enterprise HTTP IDF binaryDatabase Fundamentals # 3: What's in a database? It is worth mentioning that many people will not need to create their own database. You may never be able to create your own tables or other data structures. You may be installing an application to create a
to open the Attach Database window.3. In the Attach Database window, click the Add button in the middle of the page to open the window that locates the database file, where you select the database file (suffix) to attach. MDF)4. Click "OK" button to complete the installation of additional
) Create command objectCreates a command object using an existing Connection object and SQL statement string.(4) Execute SQL statementTo execute a command using a method of the Command objectDatabase Query ExampleExample 3 always follow the previous steps to achieve, custom a method with three parameters, the first parameter is the user name, the second parameter is the password, the third parameter uses a reference type to return the processed information. This method uses the connection object
management system developed by the Swedish MySQL AB company and is currently part of Oracle's product portfolio. While MySQL offers less functionality than large software such as Oracle, MySQL provides more than enough functionality for general personal users and small and midsize businesses, and because MYSQ L is open source software, it can significantly reduce total cost of ownership. MySQL often develops free systems with a combination of PHP, Python, and Perl software.SybaseA relational
(18): Suitable for fixed-length charactersEg: identity card (18), when fixed in length, the char type is more efficient than the varchar typevarchar (): type that is suitable for characters that cannot be fixed lengthNote: The default length of no write length is 1Text: Long text informationNchar,nvarchar,ntext:N:unicode: Supports double-byte encoding. (Kanji, Korean ...)This double-byte text with n is more suitable for storing Chinese characters.Bit: (bit) 0 or 1 (usually when BOOL is used)Eg:
Label:How the database uses tables when storing data:
Columns are called fields in the database
Rows are called records in the database
Data type:
Character data type: char, varchar, etc.
Date Time Data: datetime, etc.
Numeric type: int, float, real
Currency Data: Money
Create DATABASE: The
How the database uses tables when storing data:
Columns are called fields in the database
Rows are called records in the database
Data type:
Character data type: char, varchar, etc.
Date Time Data: datetime, etc.
Numeric type: int, float, real
Currency Data: Money
Create DATABASE: The primar
Fundamentals of Database LocksIn order to ensure the data is finished and consistent, the database system adopts the lock to realize the isolation of the transaction. The basic theory of locks used in various large databases is consistent, but there are differences in the implementation.From a relationship locked by a concurrent transaction, it can be divided int
return a DataReader object that can read multiple records from the database by DataReader.DataReader ObjectAdo. NET DataReader objects can retrieve read-only, forward-only streams of data from the data source, extracting only one record from the data source at a time. Using DataReader can improve the performance of your application and reduce system overhead. DataReader belongs to a. NET data provider, and each. NET data provider has a corresponding
set of properties. + Properties can be saved in a stream or loaded from a stream. - each key and its corresponding value in the property list is a string. */
+
AProperties properties=NewProperties ();//instantiating an object at
- //loading through the class loader
- Try {
-Properties.load (TestProperties2.class. getClassLoader (). getResourceAsStream ("Jdbc.properties")); - //getClassLoader () returns the class loader for this class. -
address, gender, just to distinguish different students. Identity columns are implemented in the following ways:
If the data for a column is of a numeric type (such as an integer), you can define the column as an identity column.
Once defined as an identity column, you also need to specify the identity seed and identity increment , respectively, and thedefault value is 1.
After defining the columns of the table, each time the data is entered at a later time, the col
---restore content starts---Database additions and deletions this is the largest database in theInster Delete Update SelectCreate and delete tables in the database (CREATE table and drop table)Commonly used keywords are where, order by, group by, and Having,limitThe CREATE table if not EXISTS table name (Field name 1 field type 1, Field Name 2 field type 2, ...);
Concurrency control is required to ensure data isolation and consistency because of the damage to the acid characteristics caused by the concurrency control of multiple transactions on the database. Problems caused by multiple transaction concurrency 1. Loss of modification (Lost update,read uncommited) T1 T2 R (a) =16 R (a) =16 W (a) =a-1 W (A) =a-1 T1 modification is lost. 2. Non-repeatable read (non-repeatable read) 2.1t1 read the data, T2 m
two numbers, the small exchange to the front, each rotation section speed after the maximum number exchange to the lastUsing a double loop to achieve bubble sortingFor example:5(n) digits are stored in a one-dimensional array, how to sortAnalysis: How many rounds the outer loop control compares, the cyclic variable iThe inner loop controls how many times each round is compared, and the loop variable JObserve the law, analyze the relationship between I and J , and finally come to a conclusionI=n
(); What if you need to enter integer data? You just need a plastic transform. int Age=int. Parse (Console.ReadLine ()); Int. The Parse () method is the function of converting a string to an integer. The specific contents of the annotation specification are as follows: 1, the class name should be used before the document comments, explain the simple function of the class and how to use. 2, the method should use comments, explain the function of the method, the meaning of the parameters, return
Properties from the popup shortcut menu. 2.in the"Database Properties"Window left"Select Page"selected in the following area"Options"object, and then the right area of the"Other Options"list, find"Status"Item, click"Restrict Access"text box, in its drop-down list, select"Single_user". 3. Click OK " " After the database name is added, the display " single user " Right-click the
:Select * from Xinxi where name= ' John Doe ' and nianling=2610, or ... "or"Select * from Xinxi where name= ' John Doe ' or nianling=2611, IN (...) In... Range ofColumn names are queried for which range to query.Select * from Xinxi where nianling in (21,22,23,24)Select * from Xinxi where name in (' John Doe ', ' Zhao Liu ')12, not...in (...) Not... Range ofSelect * from Xinxi where name is not in (' John Doe ', ' Zhao Liu ')13, wildcard% means any number of any character; Like, fuzzy query, when
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