Memanggil SQLColumns di Tabel dengan Kolom Jarang

Berlaku untuk: SQL Server Azure SQL DatabaseAzure SQL Managed InstanceAzure Synapse Analytics AnalyticsPlatform System (PDW)

Sampel ini memperlihatkan cara memanggil SQLColumns pada tabel dengan kolom jarang yang ditentukan dengan menggunakan ODBC di SQL Server Native Client.

Sampel ini tidak akan berfungsi dengan versi SQL Server apa pun yang lebih lama dari SQL Server 2008 (10.0.x).

Untuk informasi selengkapnya tentang fitur kolom jarang, lihat Dukungan Kolom Jarang di SQL Server Native Client.

Contoh

Daftar pertama adalah kode sumber C++. Ubah "MyServer" menjadi nama server yang valid. Pastikan variabel lingkungan INCLUDE Anda menyertakan direktori yang berisi sqlncli.h. Jika Anda akan membangun dan menjalankan sampel ini sebagai aplikasi 32-bit pada sistem operasi 64-bit, Anda harus membuat sumber data ODBC dengan Administrator ODBC di %windir%\SysWOW64\odbcad32.exe.

Sampel ini tersambung ke instans SQL Server default komputer Anda. Untuk menyambungkan ke instans bernama, ubah definisi sumber data ODBC untuk menentukan instans menggunakan format berikut: server\namedinstance. Secara default, SQL Server Express menginstal ke instans bernama.

Kompilasi dengan /EHsc /D, "UNICODE", dan odbc32.lib.

Daftar kode kedua ( Transact-SQL) menghapus tabel yang dibuat oleh sampel ini.

// compile with: /EHsc /D "UNICODE" odbc32.lib  
#include <windows.h>  
#include <stdio.h>  
#include <sqlext.h>  
  
#include <sqlncli.h>  
  
#define SUCCESS(x) (!((x) & 0xFFFE))  
  
#define CHKRC(stmt) rc = (stmt); \  
   if (!SUCCESS(rc)) \  
   throw (RETCODE) rc;  
  
void PrintError(SQLSMALLINT HandleType, SQLHANDLE Handle) {  
   RETCODE rc = SQL_SUCCESS;  
   SQLTCHAR szSqlState[6], szMessage[1024];  
   SQLSMALLINT i = 1, msgLen = 0;  
   SQLINTEGER NativeError;  
  
   do {  
      i = 1;  
      while (SQL_NO_DATA != (rc = SQLGetDiagRec(HandleType, Handle, i, szSqlState, &NativeError,   
         szMessage, sizeof(szMessage)/sizeof(SQLTCHAR), &msgLen)) && SUCCESS(rc)) {  
            wprintf(L"SQLState=%s, NativeError=%ld, Message=%s\r\n", szSqlState, NativeError, szMessage);  
            i++;  
      }  
   }   
   while (SQL_NO_DATA != (rc = SQLMoreResults(Handle)) && SUCCESS(rc));  
}  
  
#define STR_LEN 128 + 1  
#define REM_LEN 254 + 1  
  
void ProcessSQLColumnsResult(SQLHSTMT hstmt) {  
   SQLCHAR szSchema[STR_LEN];  
   SQLCHAR szCatalog[STR_LEN];  
   SQLCHAR szColumnName[STR_LEN];  
   SQLCHAR szTableName[STR_LEN];  
   SQLCHAR szTypeName[STR_LEN];  
   SQLCHAR szRemarks[REM_LEN];  
   SQLCHAR szColumnDefault[STR_LEN];  
   SQLCHAR szIsNullable[STR_LEN];  
  
   SQLINTEGER ColumnSize;  
   SQLINTEGER BufferLength;  
   SQLINTEGER CharOctetLength;  
   SQLINTEGER OrdinalPosition;  
  
   SQLSMALLINT DataType;  
   SQLSMALLINT DecimalDigits;  
   SQLSMALLINT NumPrecRadix;  
   SQLSMALLINT Nullable;  
   SQLSMALLINT SQLDataType;  
   SQLSMALLINT DatetimeSubtypeCode;  
   SQLLEN cbCatalog;  
   SQLLEN cbSchema;  
   SQLLEN cbTableName;  
   SQLLEN cbColumnName;  
   SQLLEN cbDataType;  
   SQLLEN cbTypeName;  
   SQLLEN cbColumnSize;  
   SQLLEN cbBufferLength;  
   SQLLEN cbDecimalDigits;  
   SQLLEN cbNumPrecRadix;  
   SQLLEN cbNullable;  
   SQLLEN cbRemarks;  
   SQLLEN cbColumnDefault;  
   SQLLEN cbSQLDataType;  
   SQLLEN cbDatetimeSubtypeCode;  
   SQLLEN cbCharOctetLength;  
   SQLLEN cbOrdinalPosition;  
   SQLLEN cbIsNullable;  
  
   SQLRETURN rc = SQL_SUCCESS;  
  
   CHKRC(SQLColumns(hstmt, L"tempdb", SQL_NTS, L"dbo", SQL_NTS, L"tbl_sparse_test", SQL_NTS, NULL, 0 ));  
  
   // Bind columns in result set to buffers  
   SQLBindCol(hstmt, 1,  SQL_C_CHAR,   szCatalog,              STR_LEN,    &cbCatalog);  
   SQLBindCol(hstmt, 2,  SQL_C_CHAR,   szSchema,               STR_LEN,    &cbSchema);  
   SQLBindCol(hstmt, 3,  SQL_C_CHAR,   szTableName,            STR_LEN,    &cbTableName);  
   SQLBindCol(hstmt, 4,  SQL_C_CHAR,   szColumnName,           STR_LEN,    &cbColumnName);  
   SQLBindCol(hstmt, 5,  SQL_C_SSHORT, &DataType,              0,          &cbDataType);  
   SQLBindCol(hstmt, 6,  SQL_C_CHAR,   szTypeName,             STR_LEN,    &cbTypeName);  
   SQLBindCol(hstmt, 7,  SQL_C_SLONG,  &ColumnSize,            0,          &cbColumnSize);  
   SQLBindCol(hstmt, 8,  SQL_C_SLONG,  &BufferLength,          0,          &cbBufferLength);  
   SQLBindCol(hstmt, 9,  SQL_C_SSHORT, &DecimalDigits,         0,          &cbDecimalDigits);  
   SQLBindCol(hstmt, 10, SQL_C_SSHORT, &NumPrecRadix,          0,          &cbNumPrecRadix);  
   SQLBindCol(hstmt, 11, SQL_C_SSHORT, &Nullable,              0,          &cbNullable);  
   SQLBindCol(hstmt, 12, SQL_C_CHAR,   szRemarks,              REM_LEN,    &cbRemarks);  
   SQLBindCol(hstmt, 13, SQL_C_CHAR,   szColumnDefault,        STR_LEN,    &cbColumnDefault);  
   SQLBindCol(hstmt, 14, SQL_C_SSHORT, &SQLDataType,           0,          &cbSQLDataType);  
   SQLBindCol(hstmt, 15, SQL_C_SSHORT, &DatetimeSubtypeCode,   0,          &cbDatetimeSubtypeCode);  
   SQLBindCol(hstmt, 16, SQL_C_SLONG,  &CharOctetLength,       0,          &cbCharOctetLength);  
   SQLBindCol(hstmt, 17, SQL_C_SLONG,  &OrdinalPosition,       0,          &cbOrdinalPosition);  
   SQLBindCol(hstmt, 18, SQL_C_CHAR,   szIsNullable,           STR_LEN,    &cbIsNullable);  
  
   try {  
      while (SQL_SUCCESS == rc) {  
         CHKRC(SQLFetch(hstmt));  
         wprintf(L"Column name: %hs\tIsNullable: %hs\tType: %hs\n", szColumnName, szIsNullable, szTypeName);  
      }  
   }  
   catch (RETCODE retcode) {  
      if (SQL_NO_DATA != retcode)  
         throw retcode;  
   }  
   SQLFreeStmt(hstmt, SQL_CLOSE);  
}  
  
int main() {  
   RETCODE rc = SQL_SUCCESS;  
   HENV henv = SQL_NULL_HENV;  
   HDBC hdbc = SQL_NULL_HDBC;  
   SQLHSTMT hstmt = SQL_NULL_HSTMT;  
   SQLTCHAR * pszConnection = L"DRIVER={SQL Server Native Client 10.0}; Server=MyServer; Trusted_Connection=Yes;";  
  
   try {  
      CHKRC(SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HENV, &henv));  
      CHKRC(SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, 0));  
      CHKRC(SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc));  
      CHKRC(SQLDriverConnect( hdbc, NULL, pszConnection, SQL_NTS, NULL, 0, NULL, SQL_DRIVER_NOPROMPT));  
      CHKRC(SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt));  
      CHKRC(SQLExecDirect(hstmt,  
         L"if object_id('tempdb.dbo.tbl_sparse_test','U') is not null drop table tempdb.dbo.tbl_sparse_test",  
         SQL_NTS));  
  
      // Create a new table  
      CHKRC(SQLExecDirect(hstmt,  
         L"create table tempdb.dbo.tbl_sparse_test (col1 int SPARSE, col2 int, col3 XML column_set for all_sparse_columns)",  
         SQL_NTS));  
  
      // Insert a row into the table  
      CHKRC(SQLExecDirect(hstmt,  
         L"insert tempdb.dbo.tbl_sparse_test (col1, col2) values (1,2)",  
         SQL_NTS));  
  
      wprintf(L"Checking default SQLColumns behavior.\nYou should not see the first sparse column.\n");  
  
      ProcessSQLColumnsResult(hstmt);  
  
      wprintf(L"\nChecking SQLColumns with the statement attribute SQL_SS_NAME_SCOPE_EXTENDED.\nYou should see all the columns\n");  
      CHKRC(SQLSetStmtAttr(hstmt, SQL_SOPT_SS_NAME_SCOPE, (SQLPOINTER)SQL_SS_NAME_SCOPE_EXTENDED, SQL_IS_SMALLINT));  
  
      ProcessSQLColumnsResult(hstmt);  
  
      wprintf(L"\nChecking SQLColumns with the statement attribute SQL_SS_NAME_SCOPE_SPARSE_COLUMN_SET.\nYou should see only the sparse columns\n");  
      CHKRC(SQLSetStmtAttr(hstmt, SQL_SOPT_SS_NAME_SCOPE, (SQLPOINTER)SQL_SS_NAME_SCOPE_SPARSE_COLUMN_SET, SQL_IS_SMALLINT));  
  
      ProcessSQLColumnsResult(hstmt);  
  
   }  
   catch (RETCODE retcode) {  
      rc = retcode;  
   }  
  
   if (!SUCCESS(rc)) {  
      if (hstmt)  
         PrintError(SQL_HANDLE_STMT, hstmt);  
      else if (hdbc)  
         PrintError(SQL_HANDLE_DBC, hdbc);  
      else if(henv)  
         PrintError(SQL_HANDLE_ENV, henv);  
   }  
  
   if (hstmt)  
      SQLFreeHandle(SQL_HANDLE_STMT, hstmt);  
   if (hdbc) {  
      SQLDisconnect(hdbc);  
      SQLFreeHandle(SQL_HANDLE_DBC, hdbc);  
   }  
   if (henv)  
      SQLFreeHandle(SQL_HANDLE_ENV, henv);  
}  

use tempdb  
IF EXISTS (SELECT name FROM sysobjects WHERE name = 'tbl_sparse_test')  
     DROP TABLE tbl_sparse_test  
GO