top
The top clause is used to specify the number of records to return. Specify a scalar after the keyword to select the first N number of records, or specify a range (with exclusive lower bound) to select the records within the range. Note that the first row is at index 0, not index 1.
例子
$ 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]
$ t1 = table(timestamp, sym, qty, price);
$ t1;
$ select top 3 * from t1;
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 |
$ select top 2:4 * from t1;
timestamp |
sym |
qty |
price |
|---|---|---|---|
09:36:51 |
MS |
2100 |
29.52 |
09:36:59 |
MS |
3200 |
30.02 |
The scalar or range specified in the top clause must be an integer(s). Variables or expressions are not supported.
$ x=2;
$ select top x * from t1;
Syntax Error: [line #2] integer constant expected after keyword top
$ select top (1+2) * from t1;
Syntax Error: [line #1] integer constant expected after keyword top
top cannot be used with the pivot by clause. It can be used with the group by clause or the context by clause (see context by).