list of aggregate functions in sql

Label:Oracle common commands and functions, do a collation, for later use, easy to consult.Common commands: Connection SqlplusCommand line to run CMD entry, such as logging in the SYS mode, the command is as follows:(1). Sqlplus "sys/zhb126 as SYSDBA" (2). Sqlplus/nolog Connect sys/zhb126 as Sysdba (3). Sqlplus Scott/tiger Start a DB instance Startup-Start the database while starting the control files, data files Startup Mount-Starts the control file

character. Select Left (' small_big ',4)4 ), string ratio more functionL CHARINDEX ()returns a specified substring in a string . now the starting position. 5 ), string manipulation functionsL QUOTENAME ()Returns a string that is enclosed by a specific character.6 ), Date function pair date and time loss Enter value to hold row operation, then returns a string, number, or day period and Time Value 7 ), based on to be The parameters of the function provide the lose into value

digitsSelect substr ('abcde', length ('abcde')-3 + 1) from dual;Get current timeSelect sysdate from dual;Set the current time formatAlter session set nls_date_format = 'dd-mon-yyyyhh: mi: ss ';Query current dateSelect current_date from dual;The next Wednesday of the current date is that daySelect next_day (sysdate, 'weday') from dual;[SQL] view plaincopyConversion functionsConvert to characterSelect to_char (sysdate, 'yyyy-mm-ddhh24: mi: ss') from du

Tags: Related summary class--Text des different production numberCorrelation function mid ()---Extract characters from a text fieldSELECT MID (Column_name,start[,length]) from table_name; column_name required. The field to extract the characters from.Start Required. Specifies the starting position (the starting value is 1).Length is optional. The number of characters to return. If omitted, the MID () function returns the remaining text.The limit ()---Returns the first few or some rows of data i

Tags: substring sele nbsp Specify space Express ack res start1, verify whether it is null, is replace ISNULL (Weight,) SELECT AVG (ISNULL (Weight, 50))From Production.Product; 2. Connect multiple strings CONCAT (ename, ' a ', Sal) SELECT CONCAT (ename, ' a ', Sal) from EMP 3. Intercept string SUBSTRING (expression, start, length) SELECT SUBSTRING (expression, start, length) from empParametersExpressionis a string, a binary string, a text, an image, a column, or an expression that contains a co

Tags:. NET data Type sub table CM type details fonts _idObjectiveIn the recent reading of other people's SQL, see some functions, such as Left (), right () and so on, what is the meaning of curiosity, after the query think it is very useful, hereby recorded. Blogs are updated regularly when new functions are encountered.———————————————————————————————————————————

function: returns part of a character, binary, text, or image expressionSyntax: SUBSTRING (expression, start, length)the substring function in SQL is used to grab a portion of a field data. The name of this function is not exactly the same in different repositories: Mysql:substr (), SUBSTRING () Oracle:substr () SQL server:substring () Parameters:An expression string, binary string, te

A SQL Server function is a structure that encapsulates one or more SQL statements.SQL Server functions are divided into two types: system functions and user-defined functions.Scalar-valued Functions: The return value of a scalar-valued function is a single value of the base

Tags: single-table ext comments List Constrain generated Yes split and easy to useHttp://www.cnblogs.com/zhijianliutang/archive/2012/10/28/2743722.htmlWhen we have a larger amount of data, we need to split the large tables into smaller tables, and queries that only access departmental data can run faster, the rationale being that the data to be scanned becomes smaller. maintenance tasks (for example, rebuilding an index or backing up a table) can also

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Source: http://dev.csdn.net/article/60/60822.shtm Detailed usage of Informix SQL Functions I. Internal functions1. Internal Aggregate functions1) count (*) returns the number of rows2) count (distinct colname) returns the number of unique values in the specified Column3) sum (colname/expression) returns the value and of the specified column or expression;4) sum

It's written in front. This series of articles is divided into four parts: 1. CLR Overview. 2. Perform CLR integration programming in Visual Studio and deploy to SQL Server, including stored procedures, triggers, custom functions, custom types, and aggregations. 3. CLR integrated programming debugging and problems encountered. 4. Use the CLR to synchronize SQL