Procedures

Translation reference to convert Teradata PROCEDURE statement to Snowflake

Description

Teradata's PROCEDURE statement is translated to Snowflake PROCEDURE syntax.

For more information on Teradata PROCEDURE, click here.

Sample Source Patterns

Create Procedure Transformation

SnowConvert Helpers Code was removed from the example. You can find them here.

SnowConvert procedure helpers region

All procedures contain a region called SnowConvert Helpers code, these are a set of variables and functions that help to emulate some Teradata functionality that is not native in JavaScript. For simplicity in the procedures samples code this region will not be shown. Some helpers are added always like EXEC and some others like FETCH, INTO, etc. are added on demand.

The region helpers code is as follows:

// REGION SnowConvert Helpers Code
	var HANDLE_NOTFOUND;
	var fetch = (count,rows,stmt) => (count && rows.next() && Array.apply(null,Array(stmt.getColumnCount())).map((_,i) => rows.getColumnValue(i + 1))) || [];
	var _RS, ROW_COUNT, _ROWS, MESSAGE_TEXT, SQLCODE = 0, SQLSTATE = '00000', ERROR_HANDLERS, ACTIVITY_COUNT = 0, INTO, _OUTQUERIES = [], DYNAMIC_RESULTS = 9;
	var formatDate = (arg) => (new Date(arg - (arg.getTimezoneOffset() * 60000))).toISOString().slice(0,-1);
	var fixBind = function (arg) {
	   arg = arg == undefined ? null : arg instanceof Date ? formatDate(arg) : arg;
	   return arg;
	};
	var EXEC = function (stmt,binds,noCatch,catchFunction,opts) {
	   try {
	      binds = binds ? binds.map(fixBind) : binds;
	      _RS = snowflake.createStatement({
	            sqlText : stmt,
	            binds : binds
	         });
	      _ROWS = _RS.execute();
	      ROW_COUNT = _RS.getRowCount();
	      ACTIVITY_COUNT = _RS.getNumRowsAffected();
	      HANDLE_NOTFOUND && HANDLE_NOTFOUND(_RS);
	      if (INTO) return {
	         INTO : function () {
	            return INTO();
	         }
	      };
		    if (_OUTQUERIES.length < DYNAMIC_RESULTS) _OUTQUERIES.push(_ROWS.getQueryId());
	      if (opts && opts.temp) return _ROWS.getQueryId();
	   } catch(error) {
	      MESSAGE_TEXT = error.message;
	      SQLCODE = error.code;
	      SQLSTATE = error.state;
	      var msg = `ERROR CODE: ${SQLCODE} SQLSTATE: ${SQLSTATE} MESSAGE: ${MESSAGE_TEXT}`;
	      if (catchFunction) catchFunction(error);
	      if (!noCatch && ERROR_HANDLERS) ERROR_HANDLERS(error); else throw new Error(msg);
	   }
	};
	var CURSOR = function (stmt,binds,withReturn) {
	   var rs, rows, row_count, opened = false, resultsetTable = '', self = this;
	   this.CURRENT = new Object;
	   this.INTO = function () {
	         return self.res;
	      };
	   this.OPEN = function (usingParams) {
	         try {
	            if (usingParams) binds = usingParams;
	            if (binds instanceof Function) binds = binds();
	            var finalBinds = binds && binds.map(fixBind);
	            var finalStmt = stmt instanceof Function ? stmt() : stmt;
	            if (withReturn) {
	               resultsetTable = EXEC(finalStmt,finalBinds,true,null,{
	                     temp : true
	                  });
	               finalStmt = `SELECT * FROM TABLE(RESULT_SCAN('${resultsetTable}'))`;
	               finalBinds = [];
	            }
	            rs = snowflake.createStatement({
	                  sqlText : finalStmt,
	                  binds : finalBinds
	               });
	            rows = rs.execute();
	            row_count = rs.getRowCount();
	            ACTIVITY_COUNT = rs.getRowCount();
	            opened = true;
	            return this;
	         } catch(error) {
	            ERROR_HANDLERS && ERROR_HANDLERS(error);
	         }
	      };
	   this.NEXT = function () {
	         if (row_count && rows.next()) {
	            this.CURRENT = new Object;
	            for(let i = 1;i <= rs.getColumnCount();i++) {
	               (this.CURRENT)[rs.getColumnName(i)] = rows.getColumnValue(i);
	            }
	            return true;
	         } else return false;
	      };
	   this.FETCH = function () {
	         self.res = [];
	         self.res = fetch(row_count,rows,rs);
	         if (opened) if (self.res.length > 0) {
	            SQLCODE = 0;
	            SQLSTATE = '00000';
	         } else {
	            SQLCODE = 7362;
	            SQLSTATE = '02000';
	            var fetchError = new Error('There are not rows in the response');
	            fetchError.code = SQLCODE;
	            fetchError.state = SQLSTATE;
	            if (ERROR_HANDLERS) ERROR_HANDLERS(fetchError);
	         } else {
	            SQLCODE = 7631;
	            SQLSTATE = '24501';
	         }
	         return self.res && self.res.length > 0;
	      };
	   this.CLOSE = function () {
	         if (withReturn && _OUTQUERIES.includes(resultsetTable)) {
	            _OUTQUERIES.splice(_OUTQUERIES.indexOf(resultsetTable),1);
	         }
	         rs = rows = row_count = undefined;
	         opened = false;
	         resultsetTable = '';
	      };
	};
	let PROCRESULTS = (...OUTPARAMS) => JSON.stringify([...OUTPARAMS,[..._OUTQUERIES]]);
	// END REGION

Teradata

REPLACE PROCEDURE my_procedure (in param1 VARCHAR(10), OUT param2 BLOB)
dynamic result sets 9
SELECT * FROM table1;

Snowflake

CREATE OR REPLACE PROCEDURE PUBLIC.my_procedure (PARAM1 STRING, PARAM2 BINARY)
RETURNS STRING
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
    // REGION SnowConvert Helpers Code
     
    EXEC(`SELECT * FROM PUBLIC.table1`,[]);
    RETURN PROCRESULTS(PARAM2);
$$

Note: The stored procedure's body in Snowflake is executed as javascript functions.

If

The transformation for the IF statement is:

Teradata

IF value = 2 THEN

Snowflake

if(value == 2){
}

Case

The transformation for the Case statement is:

Teradata

case value
when 0 then
  select * from table1
else
  update table1 set name = "SpecificValue" where id = value;
end case

Snowflake

switch(value) {
    case 0:EXEC(`SELECT * FROM PUBLIC.table1`,[]);
        break;
    default:EXEC(`UPDATE PUBLIC.table1 set name = "SpecificValue" where id = value`,[]);
        break;
}

Cursor Declare, OPEN, FETCH and CLOSE

The transformation for cursor statements is:

Teradata

CREATE PROCEDURE procedure1()               
DYNAMIC RESULT SETS 2
BEGIN

    -------- Local variables --------
    DECLARE sql_cmd VARCHAR(20000) DEFAULT ' '; 
    DECLARE num_cols INTEGER;
    
    ------- Declare cursor with return only-------
    DECLARE resultset CURSOR WITH RETURN ONLY FOR firststatement;

    ------- Declare cursor -------
    DECLARE cur2 CURSOR FOR SELECT COUNT(columnname) FROM table1;
    
    -------- Set --------
    SET sql_cmd='sel * from table1';
    
    -------- Prepare cursor --------
    PREPARE firststatement FROM sql_cmd; 
    
    -------- Open cursors --------
    OPEN resultset;		
    OPEN cur1;

    -------- Fetch -------------
    FETCH cur1 INTO val1, val2;
    
    -------- Close cursor --------
    CLOSE cur1;
END;

Snowflake

CREATE OR REPLACE PROCEDURE PUBLIC.procedure1 ()
RETURNS STRING
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
 	// REGION SnowConvert Helpers Code
	
	//------ Local variables --------
	var SQL_CMD = ` `;
	var NUM_COLS;
	var RESULTSET = new CURSOR(() => FIRSTSTATEMENT,[],true);
	//----- Declare cursor -------
	var CUR2 = new CURSOR(`SELECT
	COUNT(columnname)
	FROM PUBLIC.table1`,[],false);
	//------ Set --------
	SQL_CMD = `SELECT
	*
	FROM PUBLIC.table1`;
	//------ Prepare cursor --------
	var FIRSTSTATEMENT = SQL_CMD;
	//------ Open cursors --------
	RESULTSET.OPEN();
	CUR1.OPEN();
	
	//------ Fetch -------------
	CUR1.FETCH() && ([val1,val2] = CUR1.INTO());
	//------ Close cursor --------
	CUR1.CLOSE();
	return PROCRESULTS();
 
$$;a

While

The transformation for while statement is:

Teradata

while (counter < 10) do
    set counter = counter + 1;

Snowflake

while ( counter < 10) {
    counter = counter + 1;
}

Security

The transformation for security statements is:

Teradata

Snowflake

SQL SECURITY CREATOR

EXECUTE AS OWNER

SQL SECURITY INVOKER

EXECUTE AS CALLER

SQL SECURITY DEFINER

EXECUTE AS OWNER

FOR-CURSOR-FOR loop

The transformation for FOR-CURSOR-FOR loop is:

Teradata

REPLACE PROCEDURE Database1.Proc1()
BEGIN
    DECLARE lNumber INTEGER DEFAULT 1;
    FOR class1 AS class2 CURSOR FOR 
      SELECT COL0,
      TRIM(COL1) AS COL1ALIAS,
      TRIM(COL2),
      COL3
      FROM someDb.prefixCol
    DO
      INSERT INTO TempDB.Table1 (:lgNumber, :lNumber, (',' || :class1.ClassCD || '_Ind CHAR(1) NOT NULL'));
      SET lNumber = lNumber + 1;
    END FOR;
END;

Snowflake

CREATE OR REPLACE PROCEDURE Database1.PUBLIC.Proc1 ()
RETURNS STRING
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
    // REGION SnowConvert Helpers Code
		
    var LNUMBER = 1;
        //** MSC-WARNING - MSCEWI1023 - PERFORMANCE REVIEW - THIS LOOP CONTAINS AN INSERT, DELETE OR UPDATE STATEMENT **
	for(var CLASS2 = new CURSOR(`SELECT
	COL0,
	TRIM(COL1) AS COL1ALIAS,
	TRIM(COL2),
	COL3
	FROM someDb.PUBLIC.prefixCol`,[],false).OPEN();CLASS2.NEXT();) {
	   let CLASS1 = CLASS2.CURRENT;
	   EXEC(`INSERT INTO TempDB.PUBLIC.Table1 VALUES (:lgNumber, :1, (',' || :/*** MSC-WARNING - MSCEWI1026 - THE  VARIABLE class1.ClassCD MAY REQUIRE A CAST TO DATE, TIME OR TIMESTAMP ***/
	:2 || '_Ind CHAR(1) NOT NULL'))`,[LNUMBER,CLASS1.CLASSCD]);
	   LNUMBER = LNUMBER + 1;
	}
	CLASS2.CLOSE();
 
$$;

Note: The FOR loop present in the Teradata procedure is transformed to a FOR block in javascript that emulates its functionality.

Procedure parameters and variables referenced inside statements

The transformation for the procedure parameters and variables that are referenced inside the statements of the procedure is:

Teradata

REPLACE PROCEDURE PROC1 (param1 INTEGER, param2 VARCHAR(30))
BEGIN
    DECLARE var1          VARCHAR(1024); 
    DECLARE var2          SMALLINT;
    DECLARE weekstart date;                                 
    set weekstart= '2019-03-03';
    set var1 = 'something';
    set var2 = 123;

    SELECT * FROM TABLE1 WHERE SOMETHING = :param1;
    SELECT * FROM TABLE1 WHERE var1 = var1 AND date1 = weekstart AND param2 = :param2;
    INSERT INTO TABLE2 (col1, col2, col3, col4, col5) VALUES (:param1, :param2, var1, var2, weekstart);
END;

Snowflake

CREATE OR REPLACE PROCEDURE sfSchema.PROC1 (param1 FLOAT, param2 STRING)
RETURNS STRING
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
    // REGION SnowConvert Helpers Code
  
    var VAR1;
    var VAR2;
    var WEEKSTART;
    WEEKSTART = `2019-03-03`;
    VAR1 = `something`;
    VAR2 = 123;
    // ** MSC-WARNING - MSCEWI1022 - ONE OR MORE IDENTIFIERS IN THIS STATEMENT WERE CONSIDERED PARAMETERS BY DEFAULT. REFERENCED TABLE NOT FOUND. **
    EXEC(`SELECT * FROM PUBLIC.TABLE1 WHERE SOMETHING = :1`,[PARAM1]);
    // ** MSC-WARNING - MSCEWI1022 - ONE OR MORE IDENTIFIERS IN THIS STATEMENT WERE CONSIDERED PARAMETERS BY DEFAULT. REFERENCED TABLE NOT FOUND. **
    EXEC(`SELECT * FROM PUBLIC.TABLE1 WHERE :1 = :2 AND date1 = :3 AND param2 = :4`,[VAR1,VAR1,WEEKSTART,PARAM2]);
    // ** MSC-WARNING - MSCEWI1022 - ONE OR MORE IDENTIFIERS IN THIS STATEMENT WERE CONSIDERED PARAMETERS BY DEFAULT. REFERENCED TABLE NOT FOUND. **
    EXEC(`INSERT INTO PUBLIC.TABLE2 (col1, col2, col3, col4, col5) VALUES (:1, :2, :3, :4, :5)`,[PARAM1,PARAM2,VAR1,VAR2,WEEKSTART]);
 
$$;

Note: Whenever a procedure parameter or a variable declared inside the procedure is referenced inside a Teradata statement that has to be converted, this reference is escaped from the resulting text to preserve the original reference's functionality.

Leave

In Javascript, it's possible to use break with an additional parameter, thus emulating the behavior of a Teradata LEAVE jump.

Labels can also be emulated by using Javascript Labeled Statements.

The transformation for LEAVE statement is:

Teradata

REPLACE PROCEDURE  PROC1 ()
BEGIN
  DECLARE v_propval            VARCHAR(1024);
 
 DECLARE Cur1 cursor for 
   Select 
      propID
   from viewName.viewCol
   where propval is not null;

LABEL_WHILE:
  WHILE (SQLCODE = 0)
  DO
      IF (SQLSTATE = '02000' ) 
       THEN LEAVE LABEL_WHILE;
      END IF;
      LABEL_INNER_WHILE:
      WHILE (SQLCODE = 0)
      DO
        IF (SQLSTATE = '02000' ) 
          THEN LEAVE LABEL_INNER_WHILE;
        END IF;
      END WHILE LABEL_INNER_WHILE;
      SELECT * FROM TABLE1;
  END WHILE L1;
END;

Snowflake

CREATE OR REPLACE PROCEDURE PUBLIC.PROC1 ()
RETURNS STRING
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
 	var v_propval;
	var CUR1 = new CURSOR(`SELECT
	propID
	FROM viewName.PUBLIC.viewCol
	where propval is not null`,[],false);
	L1:while ( SQLCODE == 0 ) {
	   if (SQLSTATE == `02000`) {
	      break LABEL_WHILE;
	   }
	   LABEL_INNER_WHILE:while ( SQLCODE == 0 ) {
	      if (SQLSTATE == `02000`) {
	         break LABEL_INNER_WHILE;
	      }
	   }
	   EXEC(`SELECT * FROM PUBLIC.TABLE1`,[]);
	 }
	$$;

Getting Results from Procedures

Description of the translation

In Teradata, there are two ways to return data from a procedure. The first is through output parameters and the second through Dynamic Result Sets and Cursors. Both are shown in the following example. Each important point is explained below.

Example of returning data from a Stored Procedure

Teradata

REPLACE PROCEDURE Procedure1(OUT P1 INTEGER)               
    DYNAMIC RESULT SETS 2
    BEGIN
        DECLARE SQL_CMD,SQL_CMD_1  VARCHAR(20000) DEFAULT ' ';
        DECLARE RESULTSET CURSOR WITH RETURN ONLY FOR FIRSTSTATEMENT;
        SET SQL_CMD = 'SEL * FROM EMPLOYEE';
        PREPARE FIRSTSTATEMENT FROM SQL_CMD; 
        OPEN RESULTSET;
        SET P1 = (SEL CAST(AVG(AGE) AS INTEGER) FROM EMPLOYEE);
    END;

Snowflake

CREATE OR REPLACE PROCEDURE PUBLIC.Procedure1 (P1 FLOAT)
RETURNS STRING
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
 	// REGION SnowConvert Helpers Code
  var ..., _OUTQUERIES = [], DYNAMIC_RESULTS = 2;
  // More helpers here
 	let PROCRESULTS = (...OUTPARAMS) => JSON.stringify([...OUTPARAMS,[..._OUTQUERIES]]);
  // END REGION
  
	var SQL_CMD = ` `;
	var SQL_CMD_1 = ` `;
	var RESULTSET = new CURSOR(() => FIRSTSTATEMENT,[],true);
	SQL_CMD = `SELECT
	*
	FROM PUBLIC.EMPLOYEE`;
	var FIRSTSTATEMENT = SQL_CMD;
	RESULTSET.OPEN();
	EXEC(`(SELECT
	CAST(TRUNC(AVG(AGE)) AS int)
	FROM PUBLIC.EMPLOYEE)`,[]);
	var subQueryVariable0 = res.getColumnValue(1);
	P1 = subQueryVariable0;
	return PROCRESULTS(P1);
 
$$;

In this converted SQL, there are several conversions that take place:

The DYNAMIC RESULT SETS 2 definition is converted to a DYNAMIC_RESULTS variable.
```
var DYNAMIC_RESULTS = 2;
```
When a cursor with an WITH RETURNattribute is opened (and therefore a query is executed), its query ID is stored in the_OUTQUERIEScollection in order to be later returned. The query id is obtained by thegetQueryId()function provided in the JavaScript API for Snowflake stored procedures.
Only the first k-query-IDs are stored in the collection, where k is the value of theDYNAMIC_RESULTSvariable. This is done to emulate Teradata's behavior, which only returns the first k-opened-cursors, even if more are opened in the stored procedure.
The combination of DECLARE CURSOR WITH RETURN with PREPARE is translated to:
```
var RESULTSET = new CURSOR(() => FIRSTSTATEMENT,[],true);
```
The output parameters are supported via the return statement of the procedure. An array is created containing the value of each output parameter and the_OUTQUERIEScollection. ThePROCRESULTSfunction deals with the creation and filling of this array. See PROCRESULTS() helper for more information.
```
return PROCRESULTS(P1);
```

Example of getting data from a Stored Procedure

If the output parameters and the query IDs are returned from a procedure, a second one could call the first one to get these values, as shown below:

Teradata

CREATE PROCEDURE Procedure2()
BEGIN
    DECLARE x INTEGER;
    CALL Procedure1(x);
END;

Snowflake

CREATE OR REPLACE PROCEDURE PUBLIC.Procedure2 ()
RETURNS STRING
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
    // REGION SnowConvert Helpers Code
	
    var X;
    EXEC(`CALL PUBLIC.spSample2(?)`,[X]);
    !SQLCODE && ([X,resultset] = JSON.parse(INTO()));
$$;

The value of theP1argument fromProcedure1is returned and stored in theXvariable.
The_OUTQUERIESreturned fromProcedure1are stored in theresultsetvariable.

Known Issues

No issues were found.

MSCEWI1023 - PERFORMANCE REVIEW - THIS LOOP CONTAINS AN INSERT, DELETE OR UPDATE STATEMENT.

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hashtagDescription

hashtagSample Source Patterns

hashtagCreate Procedure Transformation

hashtagSnowConvert procedure helpers region

hashtagIf

hashtagCase

hashtagCursor Declare, OPEN, FETCH and CLOSE

hashtagWhile

hashtagSnowflake

hashtagSecurity

hashtagFOR-CURSOR-FOR loop

hashtagProcedure parameters and variables referenced inside statements

hashtagLeave

hashtagGetting Results from Procedures

hashtagDescription of the translation

hashtagExample of returning data from a Stored Procedure

hashtagExample of getting data from a Stored Procedure

hashtagKnown Issues

hashtagRelated EWIs

hashtag

Description

Sample Source Patterns

Create Procedure Transformation

SnowConvert procedure helpers region

If

Case

Cursor Declare, OPEN, FETCH and CLOSE

While

Snowflake

Security

FOR-CURSOR-FOR loop

Procedure parameters and variables referenced inside statements

Leave

Getting Results from Procedures

Description of the translation

Example of returning data from a Stored Procedure

Example of getting data from a Stored Procedure

Known Issues

Related EWIs