Differences between revisions 1 and 10 (spanning 9 versions)

SPSS Joining Data

SPSS offers several commands for joining data.

The syntax of the commands is first explained, then the equivalent(s) of standard SQL joins are listed.

Contents

SPSS Joining Data

Match Files

The MATCH FILE command is primarily used for 1:1 joins, where all cases are uniquely identified in all datasets. Try:

match files
  /file=LEFT
  /file=RIGHT
  /by ID.

Variables are taken in order from the files in order. For variables originating from more than one file, values are taken from the first file they appear in and metadata is taken from the first file with any (i.e. variable label, value labels, or missing values) metadata set.

Files

Each /FILE subcommand takes one of:

a star (*) indicating the active data set
the name of a data set
a valid filename or file handle

If the active dataset is included in a join and referenced by a star (*), that dataset will be replaced in-place by the join.

Key Variables

All of the following must be satisfied by the key variable(s) named on the /BY subcommand.

It must be defined as the same format on all files
It must be unique in each file
Each file must be pre-sorted

In other words, each join could be guarded by:

dataset activate LEFT.
sort cases by ID.
compute dup=0.
if (ID=lag(ID)) dup=1.
select if dup=0.
execute.

dataset activate RIGHT.
sort cases by ID.
compute dup=0.
if (ID=lag(ID)) dup=1.
select if dup=0.
execute.

If a key variable is a string, it must additionally be defined as the same length on all files.

Tables

The MATCH FILE command has an extension through the /TABLE subcommand. This is useful for appending higher-level variables by way of lookup tables. Try:

match files
  /file=LEFT
  /table=LOOKUP
  /by ID.

Each /TABLE subcommand takes one of:

the name of a data set
a valid filename or file handle

In the case of a MATCH FILE ... /TABLE command, the key variable(s) only need to be unique across in each /TABLE dataset. In other words, each join could be guarded by:

dataset activate LEFT.
sort cases by ID.
execute.

dataset activate LOOKUP.
sort cases by ID.
compute dup=0.
if (ID=lag(ID)) dup=1.
select if dup=0.
execute.

Update File

The UPDATE FILE command is used to overwrite values in a master file with non-null values in transaction files. Try:

update file=LEFT
  /file=TRANSACTION
  /by ID.

The final dataset contains all rows and variables from all datasets. Rows and variables originating from a transaction file are appended.

Files

Each /FILE subcommand takes one of:

a star (*) indicating the active data set
the name of a data set
a valid filename or file handle

The active dataset can be specified on a /FILE subcommand with a star (*). That dataset would then be replaced in-place by the join.

The first dataset specified on a /FILE subcommand is always the master file.

Key Variables

All of the following must be satisfied by the key variable(s) named on the /BY subcommand.

It must be defined as the same type on all files
It must be unique in each file
Each file must be pre-sorted

In other words, each join could be guarded by:

dataset activate LEFT.
sort cases by ID.
execute.

dataset activate TRANSACTION.
sort cases by ID.
compute dup=0.
if (ID=lag(ID)) dup=1.
select if dup=0.
execute.

If a key variable is a string, it must additionally be defined as the same length on all files.

Star Join

The final dataset contains only the variables specified on the SELECT and JOIN subcommand, and only the rows originating from the case file.

Note: unsupported in SPSS version 20 or earlier.

Joins

Full Join

dataset activate LEFT.
match files
  /file=*
  /file=RIGHT
  /by ID.
execute.

Left Join

dataset activate LEFT.
match files
  /file=*     /in=flag_left
  /file=RIGHT /in=flag_right
  /by ID.
select if (flag_left=1).
execute.

Right Join

dataset activate LEFT.
match files
  /file=*     /in=flag_left
  /file=RIGHT /in=flag_right
  /by ID.
select if (flag_right=1).
execute.

Inner Join

dataset activate LEFT.
match files
  /file=*     /in=flag_left
  /file=RIGHT /in=flag_right
  /by ID.
select if (flag_left=1 and flag_right=1).
execute.

CategoryRicottone

-  ⇤ ← Revision 1 as of 2021-11-12 20:49:00 → 
  Size: 4643
  Editor: DominicRicottone
  Comment:
+   ← Revision 10 as of 2022-08-24 18:15:37 → ⇥
  Size: 4706
  Editor: DominicRicottone
  Comment:
-Deletions are marked like this.
+Additions are marked like this.
 Line 1:
-= SPSS Joining =

SPSS offers three commands for joining data.
+= SPSS Joining Data =

SPSS offers several commands for joining data.

The syntax of the commands is first explained, then the equivalent(s) of standard SQL joins are listed.
-Line 13:
+Line 15:
-The `MATCH FILE` command is used for 1:1 joins, where all cases are uniquely identified.



=== Syntax and Prerequisites ===

The basic syntax for `MATCH FILE` is:
+The '''`MATCH FILE`''' command is ''primarily'' used for 1:1 joins, where all cases are uniquely identified in all datasets. Try:
-Line 28:
+Line 24:
-==== Files ====

Each `/file` subcommand takes one of:
+Variables are taken in order from the files in order. For variables originating from more than one file, values are taken from the first file they appear in and metadata is taken from the first file with any (i.e. variable label, value labels, or missing values) metadata set.



=== Files ===

Each `/FILE` subcommand takes one of:
-Line 42:
+Line 40:
-==== IDs ====

All of the following must be satisfied by the key variable(s) named on the `/in` subcommand.
+=== Key Variables ===

All of the following must be satisfied by the key variable(s) named on the `/BY` subcommand.

 1. It must be defined as the same [[SPSS/DataTypes|format]] on all files
 2. It must be unique in each file
 3. Each file must be pre-sorted

In other words, each join could be guarded by:

{{{
dataset activate LEFT.
sort cases by ID.
compute dup=0.
if (ID=lag(ID)) dup=1.
select if dup=0.
execute.

dataset activate RIGHT.
sort cases by ID.
compute dup=0.
if (ID=lag(ID)) dup=1.
select if dup=0.
execute.
}}}

If a key variable is a string, it must additionally be defined as the same length on all files.



=== Tables ===

The `MATCH FILE` command has an extension through the '''`/TABLE`''' subcommand. This is useful for appending higher-level variables by way of lookup tables. Try:

{{{
match files
  /file=LEFT
  /table=LOOKUP
  /by ID.
}}}

Each `/TABLE` subcommand takes one of:

 * the name of a data set
 * a valid filename or file handle

In the case of a `MATCH FILE ... /TABLE` command, the key variable(s) only need to be unique across in each `/TABLE` dataset. In other words, each join could be guarded by:

{{{
dataset activate LEFT.
sort cases by ID.
execute.

dataset activate LOOKUP.
sort cases by ID.
compute dup=0.
if (ID=lag(ID)) dup=1.
select if dup=0.
execute.
}}}

----



== Update File ==

The '''`UPDATE FILE`''' command is used to overwrite values in a master file with non-null values in transaction files. Try:

{{{
update file=LEFT
  /file=TRANSACTION
  /by ID.
}}}

The final dataset contains all rows and variables from all datasets. Rows and variables originating from a transaction file are appended.



=== Files ===

Each `/FILE` subcommand takes one of:

 * a star (`*`) indicating the active data set
 * the name of a data set
 * a valid filename or file handle

The active dataset can be specified on a `/FILE` subcommand with a star (`*`). That dataset would then be replaced in-place by the join.

The first dataset specified on a `/FILE` subcommand is always the master file.


=== Key Variables ===

All of the following must be satisfied by the key variable(s) named on the `/BY` subcommand.
-Line 55:
+Line 145:
-compute dup=0.
if (ID=lag(ID)) dup=1.
select if dup=0.
execute.

dataset activate RIGHT.
+execute.

dataset activate TRANSACTION.
-Line 70:
+Line 157:
+----



== Star Join ==

The final dataset contains only the variables specified on the `SELECT` and `JOIN` subcommand, and only the rows originating from the case file.

Note: unsupported in SPSS version 20 or earlier.

----



== Joins ==
-Line 125:
+Line 226:
-----



== Match Tables ==

The `MATCH FILE` command has an extension through the `/table` subcommand. This is useful for appending higher-level variables by way of lookup tables. For example, appending state-level statistics to individual-level data.



=== Syntax and Prerequisites ===

The basic syntax is:

{{{
match files
  /file=MASTER
  /table=LOOKUP1
  /by ID.
}}}



==== Files ====

Each `/file` and `/table` subcommand takes one of:

 * the name of a data set
 * a valid filename or file handle

If the active dataset is included in a join and referenced by a star (`*`), that dataset will be replaced in-place by the join.



==== IDs ====

All of the following must be satisfied by the key variable(s) named on the `/in` subcommand.

 1. It must be defined as the same type on all files
 2. Each file must be pre-sorted

A key variable must be unique across all cases in all datasets specified on a `/table` subcommand.

In other words, each join could be guarded by:

{{{
dataset activate MASTER.
sort cases by ID.
execute.

dataset activate LOOKUP.
sort cases by ID.
compute dup=0.
if (ID=lag(ID)) dup=1.
select if dup=0.
execute.
}}}

If the key variable is a string, it must additionally be defined as the same length on all files.

----



== Update File ==

The `UPDATE FILE` command is used to overwrite values in a master file with non-null values in transaction files. Cases and variables not present in the master file are appended.



=== Syntax and Prerequisites ===

The basic syntax is:

{{{
match files
  /file=MASTER
  /file=TRANSACTION1
  /by ID.
}}}



==== Files ====

Each `/file` subcommand takes one of:

 * a star (`*`) indicating the active data set
 * the name of a data set
 * a valid filename or file handle

The active dataset can be specified on a `/file` subcommand with a star (`*`). That dataset would then be replaced in-place by the join.

The first dataset specified on a `/file` subcommand is always the master file.


==== IDs ====

All of the following must be satisfied by the key variable(s) named on the `/in` subcommand.

 1. It must be defined as the same type on all files
 2. It must be unique in each file
 3. Each file must be pre-sorted

In other words, each join could be guarded by:

{{{
dataset activate MASTER.
sort cases by ID.
execute.

dataset activate LOOKUP.
sort cases by ID.
compute dup=0.
if (ID=lag(ID)) dup=1.
select if dup=0.
execute.
}}}

If a key variable is a string, it must additionally be defined as the same length on all files.

Diff for "SPSS/JoiningData"

SPSS Joining Data

Match Files

Files

Key Variables

Tables

Update File

Files

Key Variables

Star Join

Joins

Full Join

Left Join

Right Join

Inner Join