Implement SQLDescribeCol

Author: rscales

cpp/src/arrow/flight/sql/odbc/entry_points.cc

@@ -287,3 +287,13 @@ SQLRETURN SQL_API SQLSetStmtAttr(SQLHSTMT stmt, SQLINTEGER attribute, SQLPOINTER
                                  SQLINTEGER stringLength) {
   return arrow::SQLSetStmtAttr(stmt, attribute, valuePtr, stringLength);
 }
+
+SQLRETURN SQL_API SQLDescribeCol(SQLHSTMT statementHandle, SQLUSMALLINT columnNumber,
+                                 SQLWCHAR* columnName, SQLSMALLINT bufferLength,
+                                 SQLSMALLINT* nameLengthPtr, SQLSMALLINT* dataTypePtr,
+                                 SQLULEN* columnSizePtr, SQLSMALLINT* decimalDigitsPtr,
+                                 SQLSMALLINT* nullablePtr) {
+  return arrow::SQLDescribeCol(statementHandle, columnNumber, columnName, bufferLength,
+                               nameLengthPtr, dataTypePtr, columnSizePtr,
+                               decimalDigitsPtr, nullablePtr);
+}

cpp/src/arrow/flight/sql/odbc/odbc.def

@@ -28,6 +28,7 @@ EXPORTS
 	SQLColAttributeW
 	SQLColumnsW
 	SQLConnectW
+	SQLDescribeColW
 	SQLDisconnect
 	SQLDriverConnectW
 	SQLExecDirectW

cpp/src/arrow/flight/sql/odbc/odbc_api.cc

@@ -1367,4 +1367,118 @@ SQLRETURN SQLNativeSql(SQLHDBC connectionHandle, SQLWCHAR* inStatementText,
   });
 }
 
+SQLRETURN SQLDescribeCol(SQLHSTMT stmt, SQLUSMALLINT columnNumber, SQLWCHAR* columnName,
+                         SQLSMALLINT bufferLength, SQLSMALLINT* nameLengthPtr,
+                         SQLSMALLINT* dataTypePtr, SQLULEN* columnSizePtr,
+                         SQLSMALLINT* decimalDigitsPtr, SQLSMALLINT* nullablePtr) {
+  LOG_DEBUG(
+      "SQLDescribeColW called with stmt: {}, columnNumber: {}, "
+      "columnName: {}, bufferLength: {}, nameLengthPtr: {}, dataTypePtr: {}, "
+      "columnSizePtr: {}, decimalDigitsPtr: {}, nullablePtr: {}",
+      stmt, columnNumber, fmt::ptr(columnName), bufferLength, fmt::ptr(nameLengthPtr),
+      fmt::ptr(dataTypePtr), fmt::ptr(columnSizePtr), fmt::ptr(decimalDigitsPtr),
+      fmt::ptr(nullablePtr));
+  using ODBC::ODBCDescriptor;
+  using ODBC::ODBCStatement;
+
+  return ODBCStatement::ExecuteWithDiagnostics(stmt, SQL_ERROR, [=]() {
+    ODBCStatement* statement = reinterpret_cast<ODBCStatement*>(stmt);
+    ODBCDescriptor* ird = statement->GetIRD();
+    SQLINTEGER outputLengthInt;
+    SQLSMALLINT sqlType;
+
+    // Column SQL Type
+    ird->GetField(columnNumber, SQL_DESC_CONCISE_TYPE, &sqlType, sizeof(SQLSMALLINT),
+                  nullptr);
+    if (dataTypePtr) {
+      *dataTypePtr = sqlType;
+    }
+
+    // Column Name
+    if (columnName || nameLengthPtr) {
+      ird->GetField(columnNumber, SQL_DESC_NAME, columnName, bufferLength,
+                    &outputLengthInt);
+      if (nameLengthPtr) {
+        *nameLengthPtr = static_cast<SQLSMALLINT>(outputLengthInt);
+      }
+    }
+
+    // Column Size
+    if (columnSizePtr) {
+      switch (sqlType) {
+        // All numeric types
+        case SQL_DECIMAL:
+        case SQL_NUMERIC:
+        case SQL_TINYINT:
+        case SQL_SMALLINT:
+        case SQL_INTEGER:
+        case SQL_BIGINT:
+        case SQL_REAL:
+        case SQL_FLOAT:
+        case SQL_DOUBLE: {
+          ird->GetField(columnNumber, SQL_DESC_PRECISION, columnSizePtr, sizeof(SQLULEN),
+                        nullptr);
+          break;
+        }
+
+        default: {
+          ird->GetField(columnNumber, SQL_DESC_LENGTH, columnSizePtr, sizeof(SQLULEN),
+                        nullptr);
+        }
+      }
+    }
+
+    // Column Decimal Digits
+    if (decimalDigitsPtr) {
+      switch (sqlType) {
+        // All exact numeric types
+        case SQL_TINYINT:
+        case SQL_SMALLINT:
+        case SQL_INTEGER:
+        case SQL_BIGINT:
+        case SQL_DECIMAL:
+        case SQL_NUMERIC: {
+          ird->GetField(columnNumber, SQL_DESC_SCALE, decimalDigitsPtr, sizeof(SQLULEN),
+                        nullptr);
+          break;
+        }
+
+        // All datetime types (ODBC2)
+        case SQL_DATE:
+        case SQL_TIME:
+        case SQL_TIMESTAMP:
+        // All datetime types (ODBC3)
+        case SQL_TYPE_DATE:
+        case SQL_TYPE_TIME:
+        case SQL_TYPE_TIMESTAMP:
+        // All interval types with a seconds component
+        case SQL_INTERVAL_SECOND:
+        case SQL_INTERVAL_MINUTE_TO_SECOND:
+        case SQL_INTERVAL_HOUR_TO_SECOND:
+        case SQL_INTERVAL_DAY_TO_SECOND: {
+          ird->GetField(columnNumber, SQL_DESC_PRECISION, decimalDigitsPtr,
+                        sizeof(SQLULEN), nullptr);
+          break;
+        }
+
+        default: {
+          // All character and binary types
+          // SQL_BIT
+          // All approximate numeric types
+          // All interval types with no seconds component
+          *decimalDigitsPtr = static_cast<SQLSMALLINT>(0);
+        }
+      }
+    }
+
+    // Column Nullable
+    if (nullablePtr) {
+      ird->GetField(columnNumber, SQL_DESC_NULLABLE, nullablePtr, sizeof(SQLSMALLINT),
+                    nullptr);
+    }
+
+    return SQL_SUCCESS;
+  });
+}
+
 }  // namespace arrow

cpp/src/arrow/flight/sql/odbc/odbc_api.h

@@ -96,4 +96,9 @@ SQLRETURN SQLGetTypeInfo(SQLHSTMT stmt, SQLSMALLINT dataType);
 SQLRETURN SQLNativeSql(SQLHDBC connectionHandle, SQLWCHAR* inStatementText,
                        SQLINTEGER inStatementTextLength, SQLWCHAR* outStatementText,
                        SQLINTEGER bufferLength, SQLINTEGER* outStatementTextLength);
+SQLRETURN SQLDescribeCol(SQLHSTMT statementHandle, SQLUSMALLINT columnNumber,
+                         SQLWCHAR* columnName, SQLSMALLINT bufferLength,
+                         SQLSMALLINT* nameLengthPtr, SQLSMALLINT* dataTypePtr,
+                         SQLULEN* columnSizePtr, SQLSMALLINT* decimalDigitsPtr,
+                         SQLSMALLINT* nullablePtr);
 }  // namespace arrow