sql basics pdf

SQL Server 2000 has two instance databases (Sample Databases pubs): and Northwind. As with system databases, the files for the instance database are also stored in the Data folder of the MSSQL subdirectories of Microsoft SQL Server (the default installation directory). The instance database contains files as shown in table 6-2: The pubs and Northwind databases can serve as a learning tool for

Server event will not be logged. -pprecision_level Indicates the highest precision of the decimal and numeric data types. There are no spaces between-p and Precision_level. Precision_level values range from 1 to 38. When this parameter is not used, the system defaults to 28, using this parameter without indicating Specific precision, the system is considered to be 38. -sregistry_key Indicates that you want to start SQL Server based on the param

found in the parent tableWhat foreign key constraints mean to the parent table:When you make a update/delete on a parent table to update or delete a candidate key that has one or more matching rows in the child table, the behavior of the parent table depends on: the on update/on delete clause that is specified when the foreign key of the child table is defined, INNODB supports 5 ways, broken down as follows. Cascade WaySynchronize update/delete out a matching record of a child table when Update

of variables, constants, cursors, user-defined exceptions ... . BEGIN -- Program start Section SQL statements and PL-SQL statements constitute the execution statement-the code body part ... When an exception occurs in the EXCEPTION program, the exception is caught and the exception is handled. --Abnormal part ... END; -- Program End SectionAttention:1, where the decla

Original: SQL Drip 17-using the database engine stored procedures, System view queries, DBA,BI Developer Prerequisite Basics　　In the development process will encounter the need to figure out when the database was built, how many tables in this database, what is the length of the stored procedure, and so on, today, the process of working with some of the database engine stored procedures, system views and so

,....) INSERT into Persons (LastName, Address) VALUES (' Wilson ', ' champs-elysees ') The Update statement is used to modify the data in the table. UPDATE table name SET column name = new value WHERE Column name = value UPDATE person SET address = ' Zhongshan. ', city = ' nanjing ' WHERE LastName = ' Wilson ' #修改地址 (address), and add the town nameDelete statement to remove rows from a table DELETE From table name WHERE column name = value DELETE from table_name #在不删除表的情况下删除所有的行. This

): ALTER TABLE R 3.2 Modification of database data Delete a tuple (that is, delete the data): Delete from r where p; if the WHERE clause is omitted, all tuples in R are deleted Note that the Drop:delete only deletes the table data, and the drop deletes not only the table data, but also the schema of the table. Insert a tuple (that is, insert data): Insert INTO R (a1,a2,..., a) VALUES (P1,P2,..., pn) Boost: INSERT INTO R1 select A1,a2,..., A from R2 where Ak=v1 and Aj>v2 Updating tuples (that is,

to the database name is created.　　View Database　1. View all databases1 show databases;2. View the specified part of the database: Fuzzy query1 Database like ' pattern '; --pattern refers to the matching pattern:% (Percent semicolon): Indicates that multiple characters are matched. _ (Underscore): Represents a single character match.3. View the database creation statement1 Create database name; Update Database　　The database name is not modifiable.Database modification is limited to library op

Label:Getting started with T-SQL programming Mini-GamesThe basics of T-SQL programming include declaring variables, if judgments, while loops, and using some basic functions. Remember when in school, wrote a two people to fight the text output game. On the Code Alter procUsp_paly as Declare @paly1 nvarchar( -),@paly2 nvarchar( -) Declare @atk1 int,@atk2 int Decl

variable is set to be more efficient than select. Set does not support assigning values to multiple variables at the same timeSQL OUTPUT StatementsThere are two ways to output in SQL Server 1.print local variable or string 2.select local variable or string Where the SELECT statement output data is a special use of query statementsData type conversionsGrammar: Cast (expression as data type) Convert (data type, expression ", style") where "" "is an opt

--===============================--The use of SQL basics--New_value--===============================The usual methods of use are:Column column_name New_value var_nameNew_value is to assign the obtained column value to the variable name, and then the variable name can participate in subsequent processingThe following shows the usage of New_value[Email protected]> define length= "15"--Define variable length[E

When it is determined that application performance problems can be attributed to one or several time-consuming statements, tuning these statements is the responsibility of the database administrator or database application developer. Statement tuning is one of the essential skills for dealing with databases.When you face a "problem" statement, how should you analyze its problem, and finally achieve the purpose of the optimization statement? The first thing to think about is, where is the "proble

I. SQL statement WRITING rulesThe 1.SQL statement is made up of English words, and each English word is a keyword, such as SELECT.2. Many DBMS require SQL statements to end, multiple SQL statements must be separated by;3.SQL statements are case insensitive, but the table or

In the process of using SQL Server, the export of data, import is an extremely common operation because of the frequent need to centralize data from multiple different locations or to replicate data to multiple locations. We can use the bcp command to do this, but remember that the command format for BCP is a pain in the neck, Although you can view the Help files, we need powerful and simple tools to do this, and Data Transformation Services DTS provi

); The database is like Excel , and multiple tables can appear Windows authentication can only be used with native references SQL Server can interoperate with Sa=super admin Create a database Database size growth by MB growth compare average by percentage Test Test Master file. mdf test_log log file Test1 secondary data file. NDF Backup. bak Primary and log files are required, and there is only one secondary file number that is not required attachin

; Click Execute.2.2 Querying the database　　show databases;　　2.3 Deleting a database　　Drop database schooldb;　　show databases;　　3. Table Operations3.1 Creating a Table　　Create Database schooldb;Select Schooldb in the left column, and click the SQL button in the right navigation bar , such as. The following actions in the database allow you to open the SQL edit box with this button. 　　　　CREATE TABLE Student (

Tags: desc res table Ring Properties Create sel ble desSQL Server Basics First, the basic knowledge (1), Storage structure: Database--table--Data (2), Management database Add: Create DATABASE name Delete: Drop database name Query: Select name from Master. sysdatabases Modify: Alter DATABASE name (modify the files and filegroups associated with the database in SQL Server. Add or delete files and filegroups i

an irreplaceable role in the process of database development, such as the maintenance and management of database, and the maintenance of database referential integrity. Therefore, it is essential to have a good understanding of all aspects of stored procedures and triggers, both for developers and for database managers, using stored procedures, especially system stored procedures, in a profound way. In this chapter, we present a comprehensive and thorough demonstration of the various issues re

the table. You can define multiple triggers for the same operation on a table. For after triggers, you can define which triggers are first triggered and which ones are last triggered, typically using system procedure sp_settriggerorder to accomplish this task. INSTEAD of triggers represent actions that do not perform their defined operations (INSERT, UPDATE, DELETE), but only execute the trigger itself. You can define a instead of trigger on a table or a instead of trigger on a view, but you c

sessionsReply variable: Session level, valid only for the current sessionWhen a session is established, the variables are inherited from the globalView server VariablesFormat:Mysql> show [{global|session}] variables [like '];Mysql> Select @@{globa|session}.variable_nameInstance:Mysql> mysql> SELECT * from INFORMATION_SCHEMA. Global_variables where variable_name= ' some_variable_name '; View global VariablesMysql> mysql> SELECT * from INFORMATION_SCHEMA. Session_variables where variable_name= '