SnowConvert AI – Oracle – HELPERS¶

In diesem Abschnitt finden Sie Hilfsfunktionen oder -Prozeduren, mit denen Sie die funktionale Äquivalenz einiger Oracle-Features erreichen können, die in Snowflake Scripting nicht nativ unterstützt werden.

Bulk Cursor-Hilfsfunktion¶

Bemerkung

Möglicherweise ist auch die FORALL-Standardtransformation für Sie von Interesse.

Der Cursor wird durch ein OBJECT mit verschiedenen Informationen über den Zustand des Cursors simuliert. Es wird eine temporäre Tabelle erstellt, um das Resultset der Abfrage des Cursors zu speichern.

Die meisten dieser Prozeduren geben ein neues Objekt mit dem aktualisierten Status des Cursors zurück.

INIT_CURSOR¶

Diese Funktion initialisiert ein neues Objekt mit den grundlegenden Cursorinformationen

CREATE OR REPLACE FUNCTION INIT_CURSOR(NAME VARCHAR, QUERY VARCHAR)
RETURNS OBJECT
AS
$$
  SELECT OBJECT_CONSTRUCT('NAME', NAME, 'ROWCOUNT', -1, 'QUERY', QUERY, 'ISOPEN', FALSE, 'FOUND', NULL, 'NOTFOUND', NULL)
$$;

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OPEN_BULK_CURSOR¶

These procedures create a temporary table with the query of the cursor. An optional overload exists to support bindings.

CREATE OR REPLACE PROCEDURE OPEN_BULK_CURSOR(CURSOR OBJECT, BINDINGS ARRAY)
RETURNS OBJECT
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
  var query = `CREATE OR REPLACE TEMPORARY TABLE ${CURSOR.NAME}_TEMP_TABLE AS ${CURSOR.QUERY}`;
  snowflake.execute({ sqlText: query, binds: BINDINGS });
  CURSOR.ROWCOUNT = 0;
  CURSOR.ISOPEN = true;
  return CURSOR;
$$;

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CREATE OR REPLACE PROCEDURE OPEN_BULK_CURSOR(CURSOR OBJECT)
RETURNS OBJECT
LANGUAGE SQL
EXECUTE AS CALLER
AS
$$
  DECLARE
    RESULT OBJECT;
  BEGIN
    RESULT := (CALL OPEN_BULK_CURSOR(:CURSOR, NULL));
    RETURN :RESULT;
  END;
$$;

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CLOSE_BULK_CURSOR¶

Diese Prozedur löscht die temporäre Tabelle, in der das Resultset des Cursors gespeichert war, und setzt die Eigenschaften des Cursors auf ihren Ausgangszustand zurück.

CREATE OR REPLACE PROCEDURE CLOSE_BULK_CURSOR(CURSOR OBJECT)
RETURNS OBJECT
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
  var query = `DROP TABLE ${CURSOR.NAME}_TEMP_TABLE`;
  snowflake.execute({ sqlText: query });
  CURSOR.ROWCOUNT = -1;
  CURSOR.ISOPEN = false;
  CURSOR.FOUND = null;
  CURSOR.NOTFOUND = null;
  return CURSOR;
$$;

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FETCH-Hilfsfunktion¶

Due to Oracle being capable of doing the FETCH statement on different kind of scenarios, multiple procedures with overloads were created to handle each case. These helpers save the fetched values into the RESULT property in the CURSOR object.

Some of the overloads include variations when the LIMIT clause was used or not. Other overloads have a COLUMN_NAMES argument that is necessary when the FETCH statement is being done into a variable that has or contains records with column names that are different to the column names of the query.

FETCH_BULK_COLLECTION_RECORDS¶

Diese Prozeduren werden verwendet, wenn FETCH BULK in einer Sammlung von Datensätzen ausgeführt wird.

CREATE OR REPLACE PROCEDURE FETCH_BULK_COLLECTION_RECORDS(CURSOR OBJECT, LIMIT FLOAT, COLUMN_NAMES ARRAY)
RETURNS OBJECT
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
  var objectConstructArgs = [];
  if (COLUMN_NAMES) {
    for (let i = 0 ; i < COLUMN_NAMES.length ; i++) {
      objectConstructArgs.push("'" + COLUMN_NAMES[i] + "'");
      objectConstructArgs.push('$' + (i + 1));
    }
  } else {
    objectConstructArgs.push('*');
  }
  var limitValue = LIMIT ?? 'NULL';
  var query = `SELECT ARRAY_AGG(OBJECT_CONSTRUCT(${objectConstructArgs.join(', ')})) FROM (SELECT * FROM ${CURSOR.NAME}_TEMP_TABLE LIMIT ${limitValue} OFFSET ${CURSOR.ROWCOUNT})`;
  var stmt = snowflake.createStatement({ sqlText: query});
  var resultSet = stmt.execute();
  resultSet.next();
  CURSOR.RESULT = resultSet.getColumnValue(1);
  CURSOR.ROWCOUNT += CURSOR.RESULT.length;
  CURSOR.FOUND = CURSOR.RESULT.length > 0;
  CURSOR.NOTFOUND = !CURSOR.FOUND;
  return CURSOR;
$$;

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CREATE OR REPLACE PROCEDURE FETCH_BULK_COLLECTION_RECORDS(CURSOR OBJECT)
RETURNS OBJECT
LANGUAGE SQL
EXECUTE AS CALLER
AS
$$
  DECLARE
    RESULT OBJECT;
  BEGIN
    RESULT := (CALL FETCH_BULK_COLLECTION_RECORDS(:CURSOR, NULL, NULL));
    RETURN :RESULT;
  END;
$$;

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CREATE OR REPLACE PROCEDURE FETCH_BULK_COLLECTION_RECORDS(CURSOR OBJECT, LIMIT INTEGER)
RETURNS OBJECT
LANGUAGE SQL
EXECUTE AS CALLER
AS
$$
  DECLARE
    RESULT OBJECT;
  BEGIN
    RESULT := (CALL FETCH_BULK_COLLECTION_RECORDS(:CURSOR, :LIMIT, NULL));
    RETURN :RESULT;
  END;
$$;

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CREATE OR REPLACE PROCEDURE FETCH_BULK_COLLECTION_RECORDS(CURSOR OBJECT, COLUMN_NAMES ARRAY)
RETURNS OBJECT
LANGUAGE SQL
EXECUTE AS CALLER
AS
$$
  DECLARE
    RESULT OBJECT;
  BEGIN
    RESULT := (CALL FETCH_BULK_COLLECTION_RECORDS(:CURSOR, NULL, :COLUMN_NAMES));
    RETURN :RESULT;
  END;
$$;

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FETCH_BULK_COLLECTIONS¶

Diese Prozeduren werden verwendet, wenn die Anweisung FETCH in einer oder mehreren Sammlungen ausgeführt wird. Da die Spalten in dieser FETCH-Operation angegeben werden, ist eine Überschreibung für spezifische COLUMN_NAMES nicht notwendig.

CREATE OR REPLACE PROCEDURE FETCH_BULK_COLLECTIONS(CURSOR OBJECT, LIMIT FLOAT)
RETURNS OBJECT
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
  var limitClause = '';
  var limitValue = LIMIT ?? 'NULL';
  var query = `SELECT * FROM ${CURSOR.NAME}_TEMP_TABLE LIMIT ${limitValue} OFFSET ${CURSOR.ROWCOUNT}`;
  var stmt = snowflake.createStatement({ sqlText: query});
  var resultSet = stmt.execute();
  var column_count = stmt.getColumnCount();
  CURSOR.RESULT = [];
  for (let i = 0 ; i < column_count ; i++) {
    CURSOR.RESULT[i] = [];
  }

  while (resultSet.next()) {
    for (let i = 1 ; i <= column_count ; i++) {
      let columnName = stmt.getColumnName(i);
      CURSOR.RESULT[i - 1].push(resultSet.getColumnValue(columnName));
    }
  }
  CURSOR.ROWCOUNT += stmt.getRowCount();
  CURSOR.FOUND = stmt.getRowCount() > 0;
  CURSOR.NOTFOUND = !CURSOR.FOUND;
  return CURSOR;
$$;

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CREATE OR REPLACE PROCEDURE FETCH_BULK_COLLECTIONS(CURSOR OBJECT)
RETURNS OBJECT
LANGUAGE SQL
EXECUTE AS CALLER
AS
$$
  DECLARE
    RESULT OBJECT;
  BEGIN
    RESULT := (CALL FETCH_BULK_COLLECTIONS(:CURSOR, NULL));
    RETURN :RESULT;
  END;
$$;

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FETCH_BULK_RECORD_COLLECTIONS¶

Diese Prozeduren werden verwendet, wenn FETCH BULK in einem Datensatz von Sammlungen ausgeführt wird.

CREATE OR REPLACE PROCEDURE FETCH_BULK_RECORD_COLLECTIONS(CURSOR OBJECT, LIMIT FLOAT, COLUMN_NAMES ARRAY)
RETURNS OBJECT
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
  var limitValue = LIMIT ?? 'NULL';
  var query = `SELECT * FROM ${CURSOR.NAME}_TEMP_TABLE LIMIT ${limitValue} OFFSET ${CURSOR.ROWCOUNT}`;
  var stmt = snowflake.createStatement({ sqlText: query});
  var resultSet = stmt.execute();
  var column_count = stmt.getColumnCount();
  CURSOR.RESULT = {};
  if (COLUMN_NAMES)
  {
    for (let i = 0 ; i < COLUMN_NAMES.length ; i++) {
      CURSOR.RESULT[COLUMN_NAMES[i]] = [];
    }
  } else {
    for (let i = 1 ; i <= column_count ; i++) {
      let columnName = stmt.getColumnName(i);
      CURSOR.RESULT[columnName] = [];
    }
  }
  
  while (resultSet.next()) {
    for (let i = 1 ; i <= column_count ; i++) {
      let columnName = stmt.getColumnName(i);
      let fieldName = COLUMN_NAMES ? COLUMN_NAMES[i - 1] : columnName;
      CURSOR.RESULT[fieldName].push(resultSet.getColumnValue(columnName));
    }
  }
  CURSOR.ROWCOUNT += stmt.getRowCount();
  CURSOR.FOUND = stmt.getRowCount() > 0;
  CURSOR.NOTFOUND = !CURSOR.FOUND;
  return CURSOR;
$$;

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CREATE OR REPLACE PROCEDURE FETCH_BULK_RECORD_COLLECTIONS(CURSOR OBJECT)
RETURNS OBJECT
LANGUAGE SQL
EXECUTE AS CALLER
AS
$$
  DECLARE
    RESULT OBJECT;
  BEGIN
    RESULT := (CALL FETCH_BULK_RECORD_COLLECTIONS(:CURSOR, NULL, NULL));
    RETURN :RESULT;
  END;
$$;

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CREATE OR REPLACE PROCEDURE FETCH_BULK_RECORD_COLLECTIONS(CURSOR OBJECT, LIMIT INTEGER)
RETURNS OBJECT
LANGUAGE SQL
EXECUTE AS CALLER
AS
$$
  DECLARE
    RESULT OBJECT;
  BEGIN
    RESULT := (CALL FETCH_BULK_RECORD_COLLECTIONS(:CURSOR, :LIMIT, NULL));
    RETURN :RESULT;
  END;
$$;

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CREATE OR REPLACE PROCEDURE FETCH_BULK_RECORD_COLLECTIONS(CURSOR OBJECT, COLUMN_NAMES ARRAY)
RETURNS OBJECT
LANGUAGE SQL
EXECUTE AS CALLER
AS
$$
  DECLARE
    RESULT OBJECT;
  BEGIN
    RESULT := (CALL FETCH_BULK_RECORD_COLLECTIONS(:CURSOR, NULL, :COLUMN_NAMES));
    RETURN :RESULT;
  END;
$$;

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