sql empty string

String. Empty is equivalent to ""Typically used for initialization of stringsLike what:String A;Console.WriteLine (a);//error here, because there is no initialization of a And the following will not error:String a=string. Empty;Console.WriteLine (a);

Copy codeThe Code is as follows: CREATE function getcolor (@ Varchar (50), @ varchar (50 )) Returns varchar (200) As Begin Declare @ SQL varchar (2000); set @ SQL ='' -- Distinct Select @ SQL = @ SQL + color + ', 'From ( Select distinct color from

One: The value of the field of the query string type is NOT NULL for SQL:[SQL]View Plaincopy SELECT * from tb_cms_flgtinfo_a t where (T.fsta are not null and t.fsta <>'); Main: The above tb_cms_flgtinfo_a is the table name, Fsta is

1. Empty functionDescription: Replaces NULL with the specified replacement value.Syntax:ISNULL (check_expression, Replacement_value)Parameters:Check_expression: An expression that will be checked for NULL. Check_expression can be of any

35. use SQL query analyzer and SQL profilerUse SQL query AnalyzerUse SQL profilerOptimize T-SQL statementSummaryIn this chapter, we will continue with the description of the pre-stored procedures in Chapter 21st. This chapter describes how to use

Copy codeThe Code is as follows:CREATE function getcolor(@ Varchar (50), @ varchar (50 ))Returns varchar (200)AsBeginDeclare @ SQL varchar (2000); set @ SQL =''-- DistinctSelect @ SQL = @ SQL + color + ', 'From (Select distinct color from

ArticleDirectory Null, dbnull, String. Empty differences-C # reposted to students who do not know much about it, please take a closer look. Description of dbnull: Null "" And string. Empty Convert. isdbnull () Null, dbnull,

Header ("Content-type:text/html;charset=utf8");Functions of PHP Operations databasefunction Phpsql ($dbconfig, $type, $field = ", $data =array (), $condition =array (), $join =array ()) {Determine that the database connection host does not existif (!

MS SQL Server Query optimization methodThere are many reasons for the slow speed of queries, which are common1, no indexes, or no indexes (this is the most common problem with query slowness, is the flaw in programming)2, I/o throughput is small,

1. Explanation of dbnull: This class is used to indicate that no known value exists (usually used in database applications ). Program ). In database applications, empty objects are valid values of fields. This class distinguishes between null