limit

DolphinDB supports the limit clause to select a limited number of records. The limit clause can use either integers or variables representing integers.

The limit clause is similar to the top clause with the following differences:

  • The top clause cannot use negative intergers. When used with the context by clause, the limit clause can use a negative integer to select a limited number of records in the end of each group. In all other cases the limit clause can only use positive integers.

  • The limit clause can select a limited number of rows starting from a specified row.

sym = `C`MS`MS`MS`IBM`IBM`C`C`C$SYMBOL
price= 49.6 29.46 29.52 30.02 174.97 175.23 50.76 50.32 51.29
qty = 2200 1900 2100 3200 6800 5400 1300 2500 8800
timestamp = [09:34:07,09:36:42,09:36:51,09:36:59,09:32:47,09:35:26,09:34:16,09:34:26,09:38:12]
t = table(timestamp, sym, qty, price);
t;

timestamp

sym

qty

price

09:34:07

C

2200

49.6

09:36:42

MS

1900

29.46

09:36:51

MS

2100

29.52

09:36:59

MS

3200

30.02

09:32:47

IBM

6800

174.97

09:35:26

IBM

5400

175.23

09:34:16

C

1300

50.76

09:34:26

C

2500

50.32

09:38:12

C

8800

51.2

select * from t limit 2;

timestamp

sym

qty

price

09:34:07

C

2200

49.6

09:36:42

MS

1900

29.46

select * from t limit 2, 5;

timestamp

sym

qty

price

09:36:51

MS

2100

29.52

09:36:59

MS

3200

30.02

09:32:47

IBM

6800

174.97

09:35:26

IBM

5400

175.23

09:34:16

C

1300

50.76

rowOffset = 2
rowCount = 5
select * from t limit rowOffset, rowCount;

timestamp

sym

qty

price

09:36:51

MS

2100

29.52

09:36:59

MS

3200

30.02

09:32:47

IBM

6800

174.97

09:35:26

IBM

5400

175.23

09:34:16

C

1300

50.76

select * from t context by sym order by qty limit -1;

timestamp

sym

qty

price

09:36:59

MS

3200

30.02

09:35:26

IBM

5400

175.23

09:38:12

C

8800

51.29