Connect Using the SAP HANA Go Interface

The first step is to check if Go is installed, and if so, which version. To do so, enter the following command:

go version

If Go is installed, then it will return the currently installed version, such as 1.22.1.

For further details on supported versions, see SAP Note 3165810 - SAP HANA Client Supported Platforms.

In order for the shell to recognize that Go has been installed and for any go commands in future steps to be recognized, a new shell window needs to be opened.

The SAP HANA Client interface for Go, like the other SAP HANA client interfaces, except for JDBC, makes use of a C library named SQLDBC. The Go driver loads the SQLDBC library named libdbcapiHDB using cgo. For further information on the following steps, consult Set Up Your Application to Use the Go Driver Package in the SAP HANA Client Interface Programming Reference Guide. A 64-bit gcc compiler is required.

1. To check if a 64-bit gcc compiler is installed, run the following command:

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   gcc --version

   

If gcc is not installed, it can be downloaded from Download MinGW. Under WinLibs.com, you can install from winlibs.com, by scrolling to the Download section and downloading the latest release version (UCRT runtime) of the ZIP archive for Win64 to install for the x86_64 architecture, and then extracting the folder.

If command prompt isn’t showing you the installed version after running the version check command, manually add the bin folder to your path by setting it in your environment variables.

Search Edit the System Environment Variables in the Microsoft Windows Start menu and click on Environment Variables…

Look for the Path environment variable and double click to edit. Select Browse and manually browse through your File Explorer to find the bin folder.

If gcc is not installed, install the system GNU C compiler for your version of Linux. The GNU C compiler includes the gcc command required by cgo. Note that if you are using openSUSE, MinGW is included in the installation for Go through YaST.

If gcc is not installed, install the Xcode Command Line Tools if they are not already installed. These tools include the compiler and related development tools required by cgo.

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xcode-select --install    

2. Examine the Go environment by running the below command:

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   go env

   Notice that GOROOT is set to a location such as C:\go or /usr/lib64/go/1.22. This is the location that the Go SDK is installed to.

   GOPATH is set to a location such as C:\Users\user\go or $HOME/go and defines the root of your workspace which stores your codebase.

3. Set the CGO_LDFLAGS environment variable to point to the location of the libdbcapiHDB library as shown below and set the appropriate library path variable if needed.

Add a NEW variable. Set the variable name to CGO_LDFLAGS and the variable value to the location of dbcapi library: C:\SAP\hdbclient\libdbcapiHDB.dll

Ensure that the hdbclient folder is set in your Path environment variable. You can set this path by clicking on New and browsing for your hdbclient folder.

Add the following lines to the appropriate shell profile for your environment.

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export CGO_LDFLAGS=$HOME/sap/hdbclient/libdbcapiHDB.so
export LD_LIBRARY_PATH=$HOME/sap/hdbclient

Add the following lines to the appropriate shell profile for your environment.

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export CGO_LDFLAGS="$HOME/sap/hdbclient/libdbcapiHDB.dylib"
export DYLD_LIBRARY_PATH="$HOME/sap/hdbclient"

4. Go to the driver folder and create a go module.

cd C:\SAP\hdbclient\golang\src\SAP\go-hdb\driver
go mod init "SAP/go-hdb/driver"
go mod tidy

cd ~/sap/hdbclient/golang/src/SAP/go-hdb/driver
go mod init "SAP/go-hdb/driver"
go mod tidy

cd ~/sap/hdbclient/golang/src/SAP/go-hdb/driver
go mod init "SAP/go-hdb/driver"
go mod tidy

The contents of the HANA Client folder is not writeable so you may need to change the permissions on the driver folder or copy files to a new location.

1. In a shell, create a folder named go, enter the newly created directory, and open a file named goQuery.go in an editor.

mkdir %HOMEPATH%\HANAClientsTutorial\go
cd %HOMEPATH%\HANAClientsTutorial\go
notepad goQuery.go

mkdir -p $HOME/HANAClientsTutorial/go
cd $HOME/HANAClientsTutorial/go
pico goQuery.go

mkdir -p $HOME/HANAClientsTutorial/go
cd $HOME/HANAClientsTutorial/go
pico goQuery.go

2. Add the code below to goQuery.go:

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   package main
   
   import (
       "fmt"
       "database/sql"
       "log"
   
       _ "SAP/go-hdb/driver"
       )
   
   func main() {
       //Option 1, retrieve the connection parameters from the hdbuserstore
       //host, port, user name and password come from the hdbuserstore key USER1UserKey
       connectString := "hdb://?key=USER1UserKey&encrypt=true&sslValidateCertificate=false&sessionVariable:APPLICATION=goQuery.go"
   
       //Option 2, specify the connection parameters
       //connectString := "hdb://User1:Password1@999deec0-ccb7-4a5e-b317-d419e19be648.hana.prod-us10.hanacloud.ondemand.com:443?encrypt=true&sslValidateCertificate=false"
   
       //encrypt and sslValidateCertificate should be true for HANA Cloud connections
       //As of SAP HANA Client 2.6, connections on port 443 enable encryption by default
   
       fmt.Println("Connect String is " + connectString)
   
       db, err := sql.Open("hdb", connectString)
       if err != nil {
       log.Fatal(err)
       return
       }
       defer db.Close()
   
       rows, err := db.Query("SELECT NAME, ADDRESS from HOTELS.CUSTOMER")
       if err != nil {
       log.Fatal(err)
       }
       defer rows.Close()
   
       var lastName string
       var address string
       for rows.Next() {
       err = rows.Scan(&lastName, &address)
       if err != nil {
           log.Fatal(err)
       }
       fmt.Println(lastName + ": " + address)
       }
   
       err = rows.Err()
       if err != nil {
   log.Fatal(err)
       }
   }

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   Once the goQuery.go file has been updated, save and close the file.

   The sessionVariable:APPLICATION parameter sets a custom application name for the connection. This value can be viewed in the CLIENT_APPLICATION column of the M_CONNECTIONS system view and may also appear in SAP HANA telemetry data.

3. Create another go module and modify its contents:

go mod init "go/goQuery"
go mod tidy
notepad go.mod

go mod init "go/goQuery"
go mod tidy
pico go.mod

go mod init "go/goQuery"
go mod tidy
pico go.mod

4. Add the code below to go.mod under the go version line:

   Make sure the path to the driver folder is correct and make any necessary changes.

replace SAP/go-hdb/driver v0.1.0 => C:\SAP\hdbclient\golang\src\SAP\go-hdb\driver
require SAP/go-hdb/driver v0.1.0

replace SAP/go-hdb/driver v0.1.0 => $HOME/sap/hdbclient/golang/src/SAP/go-hdb/driver
require SAP/go-hdb/driver v0.1.0

replace SAP/go-hdb/driver v0.1.0 => $HOME/sap/hdbclient/golang/src/SAP/go-hdb/driver
require SAP/go-hdb/driver v0.1.0

5. Place the dbcapi shared library files in /HANAClientsTutorial/go directory by copying or dragging them into that folder. Then, run the application:

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   go run goQuery.go

   

For more information on the API’s used, consult the SAP HANA connection specific properties at Go Connection Properties, Go Database/SQL Tutorial, and Package SQL.

Visual Studio Code provides plugins for Go and can be used to debug an application.

1. If you have not already done so, download Visual Studio Code.

2. If you have not already done so, in Visual Studio Code, choose File | Add Folder to Workspace, and then add the HANAClientsTutorial folder.

   

3. Open the file goQuery.go.

   

   Visual Studio Code will recognize the go file extension and will suggest installing the Go for Visual Studio Code extension. Click Install.

   Check whether a launch.json file has been created. If not, go to the Run and Debug tab and select “Create a launch.json file.”

   

4. Open the file launch.json and add the following code

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   "env": {
       "CGO_LDFLAGS": "./libdbcapiHDB.dylib"
   }

   

   Change ./libdbcapiHDB.dylib to the correct file for your operating system: use libdbcapiHDB.dylib on macOS, libdbcapiHDB.dll on Windows, or libdbcapiHDB.so on Linux. Also ensure the dbcapi file has been copied or moved into this folder.

5. Place a breakpoint.

   

6. Select Run | Start Debugging.

   Notice that the program stops running at the breakpoint that was set.

   Observe the variable values in the leftmost pane. Step through code.

   

   Debugging can also be performed from the command line using Delve.

Congratulations! You have now created and debugged a Go application that connects to and queries an SAP HANA database.