How to Build a Database query

4 次查看（过去 30 天）
shaz
shaz 2012-4-2
Hi i have 3 variables one say Columnname tells about the database column names ,other two variable2 & variable3 tells about timestamp for eg( 03-Apr-2012 12:25:00 ).
Columnname = abcd variable2 = 03-Apr-2012 12:25:00 variable3 = 10-Apr-2012 12:25:00
after connecting to database & building query like this
data=exec(connection,'SELECT Columnname FROM TABLENMAE WHERE Columnname >= (''variable2 '') AND Columnname < (''variable3 '') ');
but i am getting data as blank.feels some issues while building query
Thanks in advance

请先登录，再回答此问题。

采纳的回答

Titus Edelhofer
Titus Edelhofer 2012-4-2
Hi,
it should probably read
data=exec(connection, ['SELECT ' Columnname ' FROM TABLENMAE WHERE ' Columnname '>=("' variable2 '") AND ' Columnname ' < ("' variable3 '") ']);
Two suggestions: it's easier if you do something like
sqlstatement = ['SELECT ...' ];
data = exec(connection, sqlstatement);
because then you can put a breakpoint on the exec line and see if your sqlstatement looks fine (e.g. copy paste to database client).
Second: use querybuilder to build your sql query ...
Titus
  2 个评论
shaz
shaz 2012-4-2
Thanks for replying..but have some issues while executing
??? No constructor 'com.mathworks.toolbox.database.sqlExec' with matching signature
found.
Error in ==> cursor.cursor at 60
curs.Cursor = com.mathworks.toolbox.database.sqlExec(curs.SQLQuery ,connect.Handle);
Error in ==> database.exec at 34
curs=cursor(connect,sqlQuery);
Titus Edelhofer
Titus Edelhofer 2012-4-2
Hi,
did you try the second? How does sqlstatement look like? Is it perhaps a cell array (because one of your variables is a cell array?). Then you would need to replace (e.g.) Columnname by Columnname{1} ...
Titus

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Database Toolbox 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by