SELECT QUERIES IN ABAP.....

Question

Can you give some idea about writing efficient select queries in ABAP?

Answer 1

Hi kishan,
  i can give you some hint from one document, please reward point.
The hit list is the set of rows determined by the WHERE clause. In other words, it is the set of table rows that the database system must take into account to respond to the query. Don’t confuse the hit list with the solution set, which is the set of rows (not necessarily from the table the query deals with) the database system returns to the program. Notice that in many cases the query’s hit list and the solution set are different.
What is the reason behind this rule? A smaller hit list saves disk I/Os by the database system and often reduces network load. Both of these factors have a strong influence on your program’s runtime performance.
How can you use ABAP to limit a hit list? First, use a WHERE clause whenever possible. Second, always try to describe the full search condition (not just part of it) within a single WHERE clause. ABAP provides a variety of arithmetical and logical operators to do this. Compared with your application program, the database server is usually the better place to evaluate search conditions.
Let me give you an example: Run a query against the flight table to produce a list of all flight dates for Lufthansa flight 0300 in 1998. Air carrier and air connection are known and can easily be used within the WHERE clause of the SELECT statement. The relevant year is also given, but at first glance it is difficult to build an appropriate search condition. Faced with this situation, you could be tempted to use the ABAP CHECK statement.
CHECK evaluates the subsequent logical expression. If it is true, the processing continues with the next statement. CHECK with a negative outcome terminates the current SELECT-ENDSELECT loop to start with the next row of the solution set, if there is one. Considering that fldateis a type D(YYYYMMDD) column of the sflighttable, a correct fragment of an ABAP program could look like this:
SELECT fldate
  FROM sflight INTO xdate
  WHERE carrid = 'LH'
    AND connid = '0300'.
  CHECK xdate = '1998'.
    WRITE: / xdate.
ENDSELECT.
With ABAP in general, CHECK does the job of pattern matching in character variables. But in the WHERE clause of a SELECT statement, pattern matching also can be done easily by applying the LIKE operator. Within the search pattern, two characters have a particular meaning: “_” stands for any one character and “%” stands for any character string. With this in mind, a better solution would be:
SELECT fldate
  FROM sflight INTO xdate
  WHERE carrid ='LH'
    AND connid ='0300'
    AND fldate LIKE '1998%'.
  WRITE: / xdate.
ENDSELECT.