sql server - T-SQL EXEC versus sp_exec -



sql server - T-SQL EXEC versus sp_exec -

i tried following:

declare @var2 nvarchar(30) declare @qsql nvarchar(100) set @var2 = n'iddelegat' exec ('select max('+ @var2 + ') idexec delegat'); set @qsql = 'select max(@varsp) idspexec delegat'; exec sp_executesql @qsql, n'@varsp nvarchar(30)', @var2;

and result:

idexec idspexec ----------------------- 500038 iddelegat

i not understand why sp_executesql not homecoming same result execute. right returned values in execute statement. seems sp_executesql not evaluate string 'iddelegat' homecoming column.

you cannot parameterize column names or table names when using sp_executesql. so, when plug in value iddelegat in exec(), getting column. when have parameter sp_executesql, getting 'iddelegat' -- string name of column.

the issue of can parameterize not explained in sql documentation. if dig far enough, this:

where can utilize parameters

you can utilize parameters placeholders literal values — either text or numeric values. commonly, parameters used placeholders in search conditions individual rows or groups (that is, in or having clauses of sql statement).

this in obscure part of documentation, has right general idea.

to help farther understand this, sql engine can compile queries parameters execution plan. this, needs know actual columns , tables in query. values -- parameters -- can plugged in after compilation step.

sql sql-server tsql execute sp-executesql

Comments

Post a Comment

Popular posts from this blog

Delphi change the assembly code of a running process -

Delphi change the assembly code of a running process - i'm trying alter address 00741fa5 has push test.009e721c . alter push test.009e71c8 . procedure callback; asm force $9e71c8 end; procedure tform2.btn1click(sender: tobject); var ppid :dword; pprocess : cardinal; begin getwindowthreadprocessid(findwindow(nil,pchar('test')), @ppid); pprocess := openprocess(process_all_access, false, ppid); injectasm(pprocess, $741fa5, 10, integer(@callback), 0); end; here injectasm function (with error checking) function injectasm(process: longword; injectaddress, injectsize, codeaddress, codesize : integer): pointer; var csize, rsize : integer; replaced : array of byte; jmp : array [0..4] of byte; jmpaddress : integer; nopv : byte; : integer; nbr: ulong_ptr; begin //injectsize must equal or greater 5, because need space our //(far) jmp wwxxyyzz instruction //if there's no space, inject in place of few instructions if injectsize ...
Read more

json - Hibernate and Jackson (java.lang.IllegalStateException: Cannot call sendError() after the response has been committed) -

json - Hibernate and Jackson (java.lang.IllegalStateException: Cannot call sendError() after the response has been committed) - hello have problem hibernate , jackson. have 2 pojos @entity @table(name = "users") public class user implements serializable { static final long serialversionuid = 4235637833262722256l; @id @generatedvalue private int id; @column(name = "creation_date") private date creationdate; @column(name = "first_name") private string firstname; @column(name = "last_name") private string lastname; @version @column(name = "version") private int version; @column(name = "e_mail") private string email; @column(name = "enabled") private boolean enabled; @column(name = "login") private string login; @column(name = "password") private string password; @jsonmanagedreference("role") @onetomany(mappedby = "user", cascade = cascadetype.all,fetch = fetchtyp...
Read more

C++ 11 "class" keyword -

C++ 11 "class" keyword - i've started using c++ 11 little bit more , have few questions on special uses of class keyword. know it's used declare class, there's 2 instances have seen don't understand: method<class t>(); and class class_name *var; why precede typename keyword class in first example, , keyword pointer in sec example? that known elaborated type specifier , necessary when class name "shadowed" or "hidden" , need explicit. class t { }; // love of god don't t t; t t2; if compiler smart, give these warnings: main.cpp:15:5: error: must utilize 'class' tag refer type 't' in scope t t2; ^ class main.cpp:14:7: note: class 't' hidden non-type declaration of 't' here t t; ^ if class not defined, deed forwards declaration. for example: template <typename t> void method() { using type = typename t::value_type; } method...
Read more