SQL join is used to query data from these tables based on the relationship between the columns in two or more tables.Join and KeySometimes in order to get the complete result, we need to get the results from two or more tables. We need to execute the join.Tables in the database can be linked by keys. The primary key (Primary key) is a column, and the value of each row in the column is unique. In the table, the value of each primary key is unique. The
Shared SQL zone, private SQL zone, and cursor
I. Share the SQL ZoneThe shared SQL zone is another way of calling the handle of the cursor object in the Library cace and the data of the Child heap.Ii. Concept of private SQL ZonePrivate S
1. Execute DDL and DDL statements (except select)
A) open a cursor.
B) analyze the statements to be executed
C) bind any input variables that may be required
D) execute the statement
E) Close the cursor.The execution of the SELECT statement is as follows:
Set serveroutput on;
Declare
V_cursorid number;
V_selectrecords varchar2 (500 );
V_numrows integer;
V_mynum integer;
V_mytext varchar (50 );
Begin
V_cursorid: = dbms_ SQL .open_cursor;
V_selectrecord
Tags: LTE tin tac hit Lex supports RAC query statement testingIn our Java development application process, will inevitably encounter the system performance problems, especially in the enterprise application development process, will deal with the database. When we encounter database performance, the most effective is to directly track the execution of each SQL statement, the optimization of SQL statements,
Label:A small SQL Server DBA wants to talk about the capabilities of SQL ServerBaidu has not yet searched for relevant individuals to write more valuable articles, at least in the Chinese network of the world there is noBut there is an article on Microsoft's website: "Comparing SQL Server with IBM DB2"The article compares from the following aspects1. TCO and ROI2
MSSQL provides us with two commands for dynamically executing SQL statements, namely exec and sp_executesql, and generally, sp_executesql has the advantage of providing an input-output interface, and exec does not. One of the biggest benefits is the ability to reuse execution plans with sp_executesql, which provides execution performance and can write more secure code. EXEC will be more flexible in some cases. Unless you have compelling reasons to use
Label:Introduction The transaction log in SQL Server is undoubtedly one of the most important parts of SQL Server. Because SQL Server uses transaction logs to ensure persistence (durability) and transaction rollback (Rollback). This also partially ensures the acid properties of the transaction. When SQL Server crashes,
Comparison of functions between Visual Basic for Applications and SQL Server Transact-SQL (ADP)Note that the information in this topic applies only to the Microsoft Access Project (. ADP ).
The following table compares common functions in Microsoft Visual Basic for Applications (VBA) and Microsoft SQL Server Transact-SQL
SQL Server 2000 T-SQL operation
T-SQL (trantsact-SQL) is a structured query language developed by Microsoft on the basis of Sybase.ProgramAnd the tools for communicating and accessing stored procedures with SQL Server. Included ansi89 and ansi92 standards. So T-
Remote connection SQL Server 2008, server-side and client configuration
Key settings:
The first step (SQL2005, SQL2008):
Start--> program-->microsoft SQL Server 2008 (or the)--> Configuration Tool-->sql Server Configuration Manager-->sql Server network configuration--> MSSQLServer (this name is the exact instance na
1. view the database version
Select @ version
2. view the operating system parameters of the machine where the database is locatedExec master .. xp_msver
3. view database startup parametersSp_configure
4. view the database startup timeSelect convert (varchar (30), login_time, 120) from Master .. sysprocesses where spid = 1
View database server name and Instance namePrint 'server name ...... + convert (varchar (30), @ servername)Print 'instance ......: '+ convert (varchar (30), @ servicename)5.
1. View the version of the database
SELECT @ @version
2. View the machine operating system parameters of the database
EXEC master.. xp_msver
3. View Database Startup Parameters
sp_configure
4. View Database Startup time
Select CONVERT (varchar, login_time,120) from master. sysprocesses where spid=1
To view the database server name and instance name
print ' Server Name ... ...: ' + CONVERT (varchar (), @ @SERVERNAME), ".
print ' Instance ....: ' + CONVERT (varchar), @ @SERVICENAME. @)., d..
5
PremiseWhen this article discusses only SQL Server queries,For non-composite statistics, where the statistics for each field contain only the data distribution of theHow to estimate the number of rows based on statistical information when combining queries with multiple fields.The algorithm principle of estimating the number of data rows using statistics from different fields, and the differences between SQL
SQL Toolbelt contains all the SQL Server tools and new versions that are currently produced by Red Gate. That is, when you work with SQL Server databases, you can easily get the set of powerful tools you need, including SQL Compare, SQL Data Compare Pro,,
Chapter 1 Basic SQL statements (Basic SQL statements) and Chapter 1 Basic SQL statements
1. query the database system time, which is usually displayed in the default format of the server (depending on the character set of the database );Note: dual is a virtual table in the database and belongs to the Administrator sys user, but all users can access it. It has no
Connect to the SQL server lock mechanism (I)-Overview (lock type and scope)
Ii. Complete lock compatibility matrix (see)
Correct Code Description: see.
III. The following table lists the resources that can be locked by the database engine.
Name
Resources
Abbreviations
Encoding
Specifies the method to describe the resource when a lock is presented.
Description
Data row
RID
RID
9
File No.: Page No.: Slot
Java. SQL. SQLException: ORA-00604: recursive SQL Level 1 error, recursive SQL Level 1 error
The following error is reported in the background:
Caused by: java. SQL. SQLException: ORA-00604: recursive SQL Level 1 error
ORA-01000: exceeds the maximum number of opened cursors
Tags: User bar implicit conversion first location assignment set size getWhat is a cursor The result set, which is the collection of all row data returned after the select query. Cursors are a mechanism for working with result sets, which can locate a row in the result set, read or write multiple data, or move the cursor to navigate to the rows you want to manipulate the data. Generally complex stored procedures, there will be the appearance of cursors, his main use is:
Navigates to a
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