The TOP statement reports a syntax error when UniDAC queries the dbf file
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- Posts: 16
- Joined: Fri 13 Dec 2019 16:39
The TOP statement reports a syntax error when UniDAC queries the dbf file
Hi,
I am trying to use UniDAC to query the data in the Visual FoxPro database. I refer to the instructions in this official document (https://blog.devart.com/delphi-component-for-dbf.html) to connect the dbf data table file, and everything is normal.
But when I use the TOP n function to query the first record in the table that is larger than a certain field, it keeps reporting "near "1"1: syntax error".
https://sm.ms/image/A9G4pHiml8vEKaF
But I use Microsoft Visual FoxPro 9 SP2 to execute the same SQL statement in the command line window and it can be executed successfully.
https://sm.ms/image/sVNEABow6dDTFPJ
I want to know where the problem is and how to deal with it.
I am trying to use UniDAC to query the data in the Visual FoxPro database. I refer to the instructions in this official document (https://blog.devart.com/delphi-component-for-dbf.html) to connect the dbf data table file, and everything is normal.
But when I use the TOP n function to query the first record in the table that is larger than a certain field, it keeps reporting "near "1"1: syntax error".
https://sm.ms/image/A9G4pHiml8vEKaF
But I use Microsoft Visual FoxPro 9 SP2 to execute the same SQL statement in the command line window and it can be executed successfully.
https://sm.ms/image/sVNEABow6dDTFPJ
I want to know where the problem is and how to deal with it.
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- Posts: 16
- Joined: Fri 13 Dec 2019 16:39
Re: The TOP statement reports a syntax error when UniDAC queries the dbf file
Hi MaximG, Could you give me some help? I'm a little anxious.
Re: The TOP statement reports a syntax error when UniDAC queries the dbf file
UniDAC uses SQL engine of SQLite for this. So you are limited to SQLite compatible SQL.
Instead of "TOP" use "LIMIT":
becomes
Instead of "TOP" use "LIMIT":
Code: Select all
SELECT TOP 10 id, name FROM foo ORDER BY id
Code: Select all
SELECT id, name FROM foo ORDER BY id LIMIT 10
Re: The TOP statement reports a syntax error when UniDAC queries the dbf file
Hi,
Devart ODBC Driver for xBase is designed with using SQLite engine, therefore to compose queries using our drivers, you can use the syntax used in SQLIte: sqlite.org/lang.html
In most cases, our driver supports the SQLite syntax. To limit the number of rows returned for a query, pelase use the LIMIT clause.
For example:
SELECT Name FROM TestTable LIMIT 1
Should you have any questions, do not hesitate to ask!
Best regards,
Sergey
Devart ODBC Driver for xBase is designed with using SQLite engine, therefore to compose queries using our drivers, you can use the syntax used in SQLIte: sqlite.org/lang.html
In most cases, our driver supports the SQLite syntax. To limit the number of rows returned for a query, pelase use the LIMIT clause.
For example:
SELECT Name FROM TestTable LIMIT 1
Should you have any questions, do not hesitate to ask!
Best regards,
Sergey
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- Posts: 16
- Joined: Fri 13 Dec 2019 16:39
Re: The TOP statement reports a syntax error when UniDAC queries the dbf file
Hi frickler, Stellar.
Thank you, I had to use Microsoft Visual FoxPro OLEDB Provider to complete the development of related functions at that time, and I will try to develop with UniDAC again.
I have a question. When using the TUniQuery component to query a dbf table(file name: 20210916.dbf), is the dbf file name after the FROM statement? Must be quoted and not include the extension?
If I don’t do this, I will always prompt: near "20210916": syntax eror.
Thank you, I had to use Microsoft Visual FoxPro OLEDB Provider to complete the development of related functions at that time, and I will try to develop with UniDAC again.
I have a question. When using the TUniQuery component to query a dbf table(file name: 20210916.dbf), is the dbf file name after the FROM statement? Must be quoted and not include the extension?
If I don’t do this, I will always prompt: near "20210916": syntax eror.
Re: The TOP statement reports a syntax error when UniDAC queries the dbf file
Hi,
Thank you for your reply.
You don't have to specify the file extension in SQL statements when querying your data with UniDAC.
[Table1.DBF]
UniQuery1.SQL.Text := 'SELECT * FROM Table1';
Kindly note that for the proper work of UniDAC the names of DBF tables must not start with numbers.
Please try to rename the table files (* .DBF, * .CDX, * .FPT, etc.), for instance:
"20210916.dbf" -> "T20210916.dbf".
"20210916.cdx" -> "T20210916.cdx".
"20210916.fpt" -> "T20210916.fpt".
Please, let us know if any other questions arise!
Sergey
Devart Team
Thank you for your reply.
You don't have to specify the file extension in SQL statements when querying your data with UniDAC.
[Table1.DBF]
UniQuery1.SQL.Text := 'SELECT * FROM Table1';
Kindly note that for the proper work of UniDAC the names of DBF tables must not start with numbers.
Please try to rename the table files (* .DBF, * .CDX, * .FPT, etc.), for instance:
"20210916.dbf" -> "T20210916.dbf".
"20210916.cdx" -> "T20210916.cdx".
"20210916.fpt" -> "T20210916.fpt".
Please, let us know if any other questions arise!
Sergey
Devart Team
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- Posts: 16
- Joined: Fri 13 Dec 2019 16:39
Re: The TOP statement reports a syntax error when UniDAC queries the dbf file
Hi,
Thank you very much for your patience, You saved my life.
Thank you very much for your patience, You saved my life.
Re: The TOP statement reports a syntax error when UniDAC queries the dbf file
Hi,
Thank you for your reply! I was happy to assist you!
In case you have any further questions about our products, please feel free to contact us any time!
Sergey
Devart Team
Thank you for your reply! I was happy to assist you!
In case you have any further questions about our products, please feel free to contact us any time!
Sergey
Devart Team