In developing T-SQL, it is often necessary to perform a variety of operations on strings, and the following describes commonly used string functions. 1. ASCII ASCII code to get charactersThe ASCII code is the standard encoding of the character. To get the ASCII code for a character, you can do so by calling the ASCII function.Syntax structure:ASCII (espression)The expression here is one that returns a char or varchar data type, and the ASCII function
number of times it appears. The default value is 1. If it is negative or 0, the system reports an error,Example: [SQL] select instr ('oracle hello Oracle hello', 'oracle ',-1, 2) from dual;Ltrim, rtrim [SQL] select RTRIM ('Hello oracle ', 'oracle') from dual; -- result: hello: delete 'oracle 'on the right'SoundexAn interesting function returns a string with the same pronunciation as a given string [
A function is a program that has 0 or more parameters and has a return value. In SQL, Oracle builds a series of functions that can be called SQL or PL/SQL statements, and functions are divided into two main classes: Single-line functions, group functions.
1, a single function in SQL
There are many types of functions
SQL statement optimization improves database performance and SQL statement database performance
In systems with unsatisfactory performance, apart from the fact that the application load exceeds the server's actual processing capacity, it is more because the system has a large number of SQL statements that need to be optimized. To achieve stable execution performa
Label:Next: T-SQL Dynamic Query (3)--Static SQLObjective: There's a lot of talk about dynamic queries, and this article describes some of the ways to use dynamic SQL to solve dynamic queries.Why use Dynamic sql: in many projects, dynamic SQL is widely used and even misused, and in many cases, dynamic
1. SQL InjectionSo far, I have hardly seen anyone who has written a very complete article, or a very mature solution (there are certainly many people who can do it, and the problem is that it has not been spread. Unfortunately) I would like to give a few simple points to inspire everyone to think about and play a role in attracting others.
I. Principles of SQL Injection There are many ways to implement and
Tags: primary key first break range Ror add comment art DropSQL PRIMARY KEY ConstraintThe PRIMARY KEY constraint uniquely identifies each record in a database table. The primary key must contain a unique value. Primary key columns cannot contain NULL values. Each table should have a primary key, and each table can have only one primary key.SQL PRIMARY KEY Constraint on CREATE TABLEThe following SQL creates the PRIMARY KEY constraint in the "id_p" colu
Today to query their own installed sqlserver2008 is R2 version, search the next, found that a lot of people query this problem, now recorded as follows, through the version of the command queryAlso understand the older brother SQL Server version of the good, a look is very clear, record
1. View SQL Server 2005/2008 version number
The code is as follows
Copy Code
Select SERVERPR
Tags: migrating local SQL Server database to Windows Azure SQL database via SSMs toolMigrate local SQL Server database to Windows Azure SQL database via the SSMs toolMicrosoft's product updates are getting faster, almost every year there are product updates, today, we mainly introduce how to migrate the local
Tags: Microsoft CTI object Complex problem: Lis use parameter BinThis article belongs to theUnderstand the mysteries of performance-slow in applications, fast in SSMS"seriesNext: Understanding the Mysteries of performance-application slow, SSMs fast (5)--case: How to deal with parameter sniffing We put aside the argument sniffing topic and went back to the original point of concern in this series: Why is the statement slow in the application, but fast in ssms? So far, it's all about the stored p
Complex SQL Split optimizationSplitting SQL is one of the most effective methods of performance optimization, which is to break down complex SQL into simple SQL by a certain logic, and finally execute an equivalent logic with the help of temporary tables, and have achieved efficient execution. I've been trying to write
Sharing the SQL area, private SQL area, and game Benchmark 1. Sharing the SQL area is another way to name the handle of the cursor object in Librarycace and the data of the Child heap. Ii. Concept of private SQL zone is stored in PGA in dedicated server mode. (Review the concept of PGA: PGA is allocated on the server s
SQL % found, SQL % notfound, SQL % rowcountWhen executing the DML (insert, update, delete) statement, you can use the following three implicit cursors (the cursor is an area in the memory that maintains the query results, which is opened when DML is run, when it is finished, use SQL % isopen to check whether it is enab
Tags: process variable assignment multiple meanings have a counter target based on nullI. T-SQL overviewThe programming language that SQL Server uses to manipulate the database is Transaction-sql, or T-SQL. T-SQL differs from PL/SQL
Label:Originally using SQL Server 2000 databases, the DTS tool makes it easy to import and export data between SQL Server and DBF files, and now, after installing SQL Server2005, discovers the SQL Server Import Export Wizard that it provides The data sources in the database are not rich in the original, and the DBF fil
entered in the numeric expression Rand returns the random float value between 0 and 1 round returns the numeric expression and rounding to the specified length or precision sign returns the positive (+ 1) of the given expression), zero (0) or negative (-1) Signs sin returns the given angle (in radians) in an approximate number (float) expression) Square returns the square of the given expression SQRT returns the square root of the given expression tan returns the tangent of the input exp
SQL Server parallel operation optimization prevents parallel operations from being restrained and affects SQL Execution efficiency and SQL Execution Efficiency
Why should I also say SQL Server Parallelism:
I have written many articles about SQL Server parallelism in the gard
What should I do if SQL Server executes dynamic SQL statements? The following describes the two correct ways for SQL Server to execute dynamic SQL. We hope that you can have a better understanding of SQL Server to execute dynamic SQL
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
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