Excel connection strings

CData ADO.NET Provider for Excel

Standard
Excel File=C:\myExcelFile.xlsx;
No headers in Excel sheet
Excel File=C:\myExcelFile.xlsx;Header=False;
Pseudo column names (A,B,C) are used instead.
Caching data
Excel File=C:\myExcelFile.xlsx;Cache Location=C:\cache.db;Auto Cache=true; Offline=false;
To retrieve data from the cache, add "#Cache" to the table name. For example, to query cached data from the "Sheet" table, execute "SELECT * FROM [Sheet#Cache]".
Caching data and metadata
Excel File=C:\myExcelFile.xlsx;Cache Location=C:\cache.db;Auto Cache=true; Offline=false;Cache Metadata=true;
The table metadata will also be cached instead of retrieving it from the data source. This improves connection performance. Read more here →
Cached data only / Offline mode
Excel File=C:\myExcelFile.xlsx;Offline=true;Query Passthrough=true; Cache Location=C:\cache.db;
SELECT statements will always retrieve data from the cache. DELETE/UPDATE/INSERT statements is not allowed and will throw an exception.
Using an External Cache Provider

RSSBus drivers have the ability to cache data in a separate database such as SQL Server or MySQL instead of in a local file using the following syntax:
Cache Provider=Provider.Namespace; Cache Connection='Connection String to Cache Database';
Above is just an example to show how it works. It can be used both with "Auto Cache" and with "Cached Data Only / Offline Mode". Read more about using RSSBus Cache Provider in this article >>>
Empty cells always NULL
Excel File=C:\myExcelFile.xlsx;Empty Text Mode=EmptyAsNull;
Empty cells always empty string
Excel File=C:\myExcelFile.xlsx;Empty Text Mode=NullAsEmpty;
Suppress formula calculation errors
Excel File=C:\myExcelFile.xlsx;Ignore Calc Error=true;
Read "tilted sheets", where rows are headers and columns are rows
Excel File=C:\myExcelFile.xlsx;Orientation=Horizontal;
Do not use formulas, only values

Do not treat values starting with equals (=) as formulas during inserts and updates.
Excel File=C:\myExcelFile.xlsx;Allow Formula=false;

↯ Problems connecting?

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Microsoft ACE OLEDB 12.0

Xlsx files

Connect to Excel 2007 (and later) files with the Xlsx file extension. That is the Office Open XML format with macros disabled.
Provider=Microsoft.ACE.OLEDB.12.0;Data Source=c:\myFolder\myExcel2007file.xlsx; Extended Properties="Excel 12.0 Xml;HDR=YES";
"HDR=Yes;" indicates that the first row contains columnnames, not data. "HDR=No;" indicates the opposite.
Treating data as text

Use this one when you want to treat all data in the file as text, overriding Excels column type "General" to guess what type of data is in the column.
Provider=Microsoft.ACE.OLEDB.12.0;Data Source=c:\myFolder\myExcel2007file.xlsx; Extended Properties="Excel 12.0 Xml;HDR=YES;IMEX=1";
If you want to read the column headers into the result set (using HDR=NO even though there is a header) and the column data is numeric, use IMEX=1 to avoid crash.
To always use IMEX=1 is a safer way to retrieve data for mixed data columns. Consider the scenario that one Excel file might work fine cause that file's data causes the driver to guess one data type while another file, containing other data, causes the driver to guess another data type. This can cause your app to crash.
Xlsb files

Connect to Excel 2007 (and later) files with the Xlsb file extension. That is the Office Open XML format saved in a binary format. I e the structure is similar but it's not saved in a text readable format as the Xlsx files and can improve performance if the file contains a lot of data.
Provider=Microsoft.ACE.OLEDB.12.0; Data Source=c:\myFolder\myBinaryExcel2007file.xlsb; Extended Properties="Excel 12.0;HDR=YES";
You can also use this connection string to connect to older 97-2003 Excel workbooks.
"HDR=Yes;" indicates that the first row contains columnnames, not data. "HDR=No;" indicates the opposite.
Xlsm files

Connect to Excel 2007 (and later) files with the Xlsm file extension. That is the Office Open XML format with macros enabled.
Provider=Microsoft.ACE.OLEDB.12.0;Data Source=c:\myFolder\myExcel2007file.xlsm; Extended Properties="Excel 12.0 Macro;HDR=YES";
"HDR=Yes;" indicates that the first row contains columnnames, not data. "HDR=No;" indicates the opposite.
Excel 97-2003 Xls files with ACE OLEDB 12.0

You can use this connection string to use the Office 2007 OLEDB driver (ACE 12.0) to connect to older 97-2003 Excel workbooks.
Provider=Microsoft.ACE.OLEDB.12.0;Data Source=c:\myFolder\myOldExcelFile.xls; Extended Properties="Excel 8.0;HDR=YES";
"HDR=Yes;" indicates that the first row contains columnnames, not data. "HDR=No;" indicates the opposite.

Microsoft Jet OLE DB 4.0

Standard (Excel)
Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\MyExcel.xls; Extended Properties="Excel 8.0;HDR=Yes;IMEX=1";
How to Use JET in 64 bit environments
Standard alternative

Try this one if the one above is not working. Some reports that Excel 2003 need the exta OLEDB; section in the beginning of the string.
OLEDB;Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\MyExcel.xls; Extended Properties="Excel 8.0;HDR=Yes;IMEX=1";
"HDR=Yes;" indicates that the first row contains columnnames, not data. "HDR=No;" indicates the opposite.
"IMEX=1;" tells the driver to always read "intermixed" (numbers, dates, strings etc) data columns as text. Note that this option might affect excel sheet write access negative.
SQL syntax "SELECT [Column Name One], [Column Name Two] FROM [Sheet One$]". I.e. excel worksheet name followed by a "$" and wrapped in "[" "]" brackets.
"SELECT * FROM [Sheet1$a5:d]", start picking the data as of row 5 and up to column D.
Check out the [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Jet\4.0\Engines\Excel] located registry REG_DWORD "TypeGuessRows". That's the key to not letting Excel use only the first 8 rows to guess the columns data type. Set this value to 0 to scan all rows. This might hurt performance. Please also note that adding the IMEX=1 option might cause the IMEX feature to set in after just 8 rows. Use IMEX=0 instead to be sure to force the registry TypeGuessRows=0 (scan all rows) to work.
If the Excel workbook is protected by a password, you cannot open it for data access, even by supplying the correct password with your connection string. If you try, you receive the following error message: "Could not decrypt file."
A workaround for the "could not decrypt file" problem

.NET Framework Data Provider for OLE DB

Use an OLE DB provider from .NET
Provider=any oledb provider's name;OledbKey1=someValue;OledbKey2=someValue;

See the respective OLEDB provider's connection strings options. The .net OleDbConnection will just pass on the connection string to the specified OLEDB provider. Read more here.

Microsoft Excel 2007 ODBC Driver

Standard
Driver={Microsoft Excel Driver (*.xls, *.xlsx, *.xlsm, *.xlsb)}; DBQ=C:\MyExcel.xlsx;
Standard (for versions 97 - 2003)
Driver={Microsoft Excel Driver (*.xls, *.xlsx, *.xlsm, *.xlsb)}; DBQ=C:\MyExcel.xls;

Microsoft Excel ODBC Driver

Standard
Driver={Microsoft Excel Driver (*.xls)};DriverId=790;Dbq=C:\MyExcel.xls; DefaultDir=c:\mypath;
SQL syntax "SELECT [Column Name One], [Column Name Two] FROM [Sheet One$]". I.e. excel worksheet name followed by a "$" and wrapped in "[" "]" brackets.
Specify ReadOnly

[Microsoft][ODBC Excel Driver] Operation must use an updateable query. Use this connection string to avoid the error.
Driver={Microsoft Excel Driver (*.xls)};Dbq=C:\MyExcel.xls;ReadOnly=0;
ReadOnly = 0 specifies the connection to be updateable.

.NET Framework Data Provider for ODBC

Use an ODBC driver from .NET
Driver={any odbc driver's name};OdbcKey1=someValue;OdbcKey2=someValue;

See the respective ODBC driver's connection strings options. The .net OdbcConnection will just pass on the connection string to the specified ODBC driver. Read more here.