modify()
Here’s how to use modify() function.
r .modify( x i : F i , … )
Description:
Modify the field values of a record.
Syntax:
r.modify(xi:Fi,…)
Note:
The function modifies the field values in record r
Parameter:
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r |
The record to be modified |
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xi |
Modification expression |
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Fi |
Name of the field to be modified. The ith field in r will be modified if Fi isn’t supplied. |
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r' |
The new record that will replace record r |
Option:
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@r(r') |
Replace record r with record r' according to the former’s order |
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@f(r') |
Modify a certain field value of record r with record r' |
Return value:
The modified record r
Example:
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A |
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1 |
=[[1,"Lucy",29]].new(~(1):ID,~(2):Name,~(3):Age) |
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2 |
=A1(1).modify(2,"Petter") |
Modify the first and the second field |
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3 |
=A2.modify(30:Age) |
Modify Age field |
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4 |
=A3.modify(3,33:Age) |
Modify the first field and Age field |
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5 |
=[[4,"Lily",23]].new(~(1):SID,~(2):SName,~(3):SAge) |
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6 |
=A4.modify@r(A5(1)) |
Fill members of A5(1) in A4 according to A4’s order |
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7 |
=A6.modify@f(([["ella"]].new(~(1):Name))(1)) |
Modify only the value of Name field in A6 |
Related function:
T. modify()
Description:
Modify field values in a table sequence.
Syntax:
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T.modify(k,xi:Fi,…) |
Modify the kth record, which is equal to T(k).modify(xi:Fi,…) |
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T.modify(k:A,xi:Fi,…) |
Modify the records from the kth record to the (k+|A|-1)th record |
Note:
The function modifies one or more records at the specified position(s). Automatically update the index, if any, and check distinctness.
Parameter:
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k |
The position at which the record will be modified. If k exceeds the limit, then append a new record in the end. |
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xi |
The value of Fi field to be modified |
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Fi |
Name of the field of the record which will be modified. If Fi is omitted, then modify the ith field of T. |
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T |
A table sequence |
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A |
A sequence or an integer; If A is an integer, then it is equal to to(A) |
Option:
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@n |
Return the newly-modified record or sequence |
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@r(k:A) |
Modify table sequence T using squence A from the kth record according to the order of the fields |
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@f(k:A) |
Modify table sequence T using squence A from the kth record; only the common fields are modified. |
Return value:
Return the updated record or sequence
Example:
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A |
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1 |
=demo.query("select * from DEPARTMENT") |
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2 |
=A1.modify(1,"Sales",5) |
Modify the first and the second fields of the first record |
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3 |
=A1.modify(2,6:MANAGER) |
Modify the MANAGER field of the second record
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4 |
=A1.modify@n(2:1,"AAA":DEPT,76:MANAGER) |
Return the modified second record |
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5 |
=create(DeptName,ManagerID) |
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6 |
=A5.modify(1:A1,DEPT:DeptName,MANAGER:ManagerID) |
Append a new record in the end because 1 exceeds the limit |
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7 |
=A1.delete(A1.select(MANAGER>5)) |
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8 |
=A5.modify@r(1:A7) |
Modify A5 using A7 from the first record |
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9 |
=create(DeptName,MANAGER) |
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10 |
=A9.modify@f(1:A7) |
Modify MANAGER field only |
Related function:
A. modify()
Description:
Assign value(s) to one or more members of a sequence according to the specified position(s).
Syntax:
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A.modify(k,x) |
Assign x to the kth member of sequence A |
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A.modify(k,X) |
Assign members of X to members of A in order from the kth position to the (k+|X|-1)th position; do the assignment backward from the end when k<0 |
Note:
The function assigns x to the kth member of sequence A or members of X to the members of A from the kth position to the number (k+|X|-1)th position in order.
Parameter:
|
A |
A sequence |
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k |
A member position; If k is greater than the length of sequence A, then append the member in the end |
|
x |
A member value |
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X |
A sequence |
Option:
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@n |
Return the modified record or a record sequence of modified records |
Return value:
A sequence
Example:
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A |
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1 |
=["a","c","d","e","f"] |
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2 |
=A1.modify(2,"g") |
[a,g,d,e,f] |
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3 |
=A1.modify(6,[2,4,5]) |
[a,g,d,e,f,2,4,5]; append the values at the end as the specified position execeeds the limit |
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4 |
=demo.query("select * from STUDENTS") |
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5 |
=A4.modify@n(2:3,ID+10:ID) |
Return a record sequence of modified records |
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6 |
=A1. modify(-2,"h") |
Assign values backward and return [a,g,d,e,f,2,4,h,5] as parameter k<0 |
Related function: