attach()

Read(808) Label: attach,

Here’s how to use attach() functions.

T.attach( T’ )

Description:

Retrieve an attached table from a cluster composite table.

Syntax:

T.attach(T’)

Note:

The function retrieves attached table T’, which should already exist, from cluster composite table T.

Parameter:

T

A cluster composite table

T’

An attached table

Return value:

An attached table

Example:

Add an attached table to composite table emp1.ctx:

 

A

 

1

=file("D:\\emp1.ctx")

 

2

=A1.create(#EID,NAME)

Create the composite table’s base table

3

=demo.cursor("select EID,NAME from employee ")

 

4

=A2.append(A3)

Append records to the base table

5

=A2.attach(t1, SURNAME,DEPT )

Add attached table t1 to the base table

6

=demo.cursor("select EID,SURNAME,DEPT from employee")

 

7

=A5.append(A6)

Append records to attached table t1

8

=A2.attach(t2,GENDER,SALARY)

Add attached table t2 to the base table

9

=demo.cursor("select EID,GENDER,SALARY from employee ")

 

10

=A8.append(A9)

Append records to attached table t2

 

Put emp1.ctx in node 192.168.0.116:8281:

 

A

 

1

=file("emp1.ctx",["192.168.0.116:8281"])

Open a cluster file

2

=A1.open()

Return a cluster composite table

3

=A2.attach(t1)

Retrieve attached table t1

T.attach( T’,C… )

Description:

Add an attached table to the base table of a composite table.

Synatx:

T.attach(T’,C…)

Note:

The function adds attached table T’ to a composite table’s base table T. A composite table can have one or multiple attached tables. The attached table’s dimensions include the dimensions of its base table; its column names should be different from the base table’s column names.

Parameter:

T

A base table

T’

An attached table

C

Attached table column, can be omitted; return an attached table named T’ if it is absent; a C preceded by # is a dimension

Return value:

An attached table

Example:

 

A

 

1

=file("D:/ctb.ctx")

 

2

=A1.create(#k1,v1)

Create the composite table’s base table where k1 is the dimension and v1 is the column

3

=A2.attach(table2,#k2,v2)

Add attached table table2 to A2’s base table; k1 and k2 are the attached table’s dimensions and v1 and v2 are its columns

4

=A2.attach(table3,v3)

Add attached table table3 to A2’s base table; k1 is the attached table’s dimension and v1 and v3 are its columns