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 1.16.

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

If it is not installed, download it from Download Go, run the installer, follow the provided instructions, and ensure that Go is in your path.

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.

Before proceeding, ensure you can create and run an example Go program as described in Test your installation.

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 Build the Go Driver 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 it is not installed, on Linux install the System GNU C compiler.

   On Windows, it can be downloaded from Download MinGW. Under Mingw-builds, select Installation: Sourceforge to run the installer.

   During the install, set the architecture option to x86_64.

   

   Add the bin folder to your path.

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/local/go. 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. Copy the SAP HANA client source code to the Go workspace.

   Shell (Windows)

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   mkdir %GOPATH%\src
   xcopy C:\SAP\hdbclient\golang\src %GOPATH%\src\ /s
   

   Shell (Linux or Mac)

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   mkdir -p $HOME/go/src
   cp -r ~/sap/hdbclient/golang/src/SAP $HOME/go/src/
   

   The results are shown in the screenshot below:

   

4. Set the CGO_LDFLAGS environment variable to point to the location of libdbcapiHDB library as shown below. The GO111MODULE variable is required in GO versions >= 1.16 and is described further at New module changes in Go 1.16. Preferably, set these values in the Microsoft Windows environment variables dialog or on Linux/Mac in the .profile or .bash_profile file so these values persist and can be seen by other applications such as Visual Studio Code.

   Shell (Windows)

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   set CGO_LDFLAGS=c:\sap\hdbclient\libdbcapiHDB.dll
   set GO111MODULE=auto
   

   Shell (Linux)

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   export CGO_LDFLAGS=$HOME/sap/hdbclient/libdbcapiHDB.so
   export GO111MODULE=auto
   

   Shell (Mac)

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   export CGO_LDFLAGS=$HOME/sap/hdbclient/libdbcapiHDB.dylib
   export GO111MODULE=auto
   

5. Run the install for the driver:

   Shell (Windows)

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   cd c:\sap\hdbclient\golang\src
   go install SAP/go-hdb/driver
   

   Shell (Linux or Mac)

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   cd ~/sap/hdbclient/golang/src
   go install SAP/go-hdb/driver
   

   The result of this should be that a new go-hdb package is installed into the GOPATH folder.

   

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

   Shell (Microsoft Windows)

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

   Shell (Linux or Mac)

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   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"
   
     //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 HOTEL.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)
     }
   }
   

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

3. On Linux or Mac, add the libdbcapiHDB library to the path so that the Go driver can find it. You may do this by adding the following lines to the .profile or .bash_profile files:

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   export LD_LIBRARY_PATH=~/sap/hdbclient
   

   Shell (Mac)

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   export DYLD_LIBRARY_PATH=~/sap/hdbclient
   

   If the next step to run the application fails with an error message of “Library not loaded”, a workaround to place the libdbcapiHDB library in the same directory as the application executable is available.

   Shell (Mac)

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   cp ~/sap/hdbclient/libdbcapiHDB.dylib .
   

4. Run the application:

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   go run goQuery.go
   

   

5. For more information on the API’s used, consult the SAP HANA connection specific properties at Connect to SAP HANA from Go, 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.

4. Place a breakpoint.

   

5. 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.

   

   Note that 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.