Understanding Relational Databases Basic Concepts and Applications for Qualitative Content Analysis

Databases as Collections of Objects A relational database holds a set of objects of different types A relational database holds a set of objects of different types Tables Tables Queries Queries Forms Forms Reports Reports Macros Macros

What Database Objects Do Tables contain the actual data Tables contain the actual data Forms simplify entering and viewing data Forms simplify entering and viewing data Queries let you view parts of the data Queries let you view parts of the data Reports format and print selected data Reports format and print selected data Macros let you automate command sequences Macros let you automate command sequences

Tables as Database Objects One database can hold many tables One database can hold many tables The tables hold different kinds of data The tables hold different kinds of data Data can be linked between tables Data can be linked between tables The link between tables is a RELATION The link between tables is a RELATION Table ATable B

What is Related? We say the two TABLES are related We say the two TABLES are related We really mean certain RECORDS in the two tables are related We really mean certain RECORDS in the two tables are related Ability to relate records in multiple tables gives relational databases their power Ability to relate records in multiple tables gives relational databases their power

Using the Relations Linked records can be ENTERED using a data entry form that combines tables and automates the linkage Linked records can be ENTERED using a data entry form that combines tables and automates the linkage Linked records can be viewed together in queries that show only what you want Linked records can be viewed together in queries that show only what you want Linked records can be combined in reports Linked records can be combined in reports

One-to-One Relationship Record 1 Record 2 Record 3 Record 4 Table A Record 1 Record 2 Record 3 Record 4 Table B

One-to-Many Relationship Record 1 Record 2 Record 3 Record 4 Table A Record 1A Record 1B Record 1C Record 2A Record 2B Record 3A Record 3B Record 3C Record 3D Record 4A Record 4B Table B

Many Tables Can Be Linked Table A Table B Table C Table D Lookup Table E

Main Table with Many Fields Main ID field to link records to other tables PLUS fields for different pieces of data: Fields data occurs once in one record Fields data occurs once in one recordOR Field is coded present or absent in record Field is coded present or absent in recordOR Field has mutually exclusive codes Field has mutually exclusive codes

Subtable to Collect One Topic Multiple ID fields Multiple ID fields Unique ID for each record in subtable Unique ID for each record in subtable Field for ID to link to main table Field for ID to link to main table Sequence field counts records linked to one case Sequence field counts records linked to one case Fields for one special set of data Fields for one special set of data text field to hold actual terms, uncoded text field to hold actual terms, uncoded code field to hold the codes for the terms code field to hold the codes for the terms possibly memo field to hold context of terms use possibly memo field to hold context of terms use might add other information related to terms use might add other information related to terms use

Two Common Subtable Situations Partial Code Known ID fields (numeric) ID fields (numeric) Numeric field for Known Codes* Numeric field for Known Codes* Text field for Uncoded Terms Text field for Uncoded Terms *May link to lookup table that holds codes *May link to lookup table that holds codes No Code Known Yet ID fields (numeric) ID fields (numeric) Text field for terms Text field for terms Later add numeric field for codes Later add numeric field for codes Could have context memo field Could have context memo field Could have other usage fields Could have other usage fields (Could create lookup table later to hold the code categories) (Could create lookup table later to hold the code categories)

Lookup Table Holds a Code ID field is the numeric code ID field is the numeric code Second field has code names Second field has code names Third field can hold descriptions of codes Third field can hold descriptions of codes It holds the CODE but not the actual data It holds the CODE but not the actual data Lookup Table Code 1 Code 2 Code 3 Collection Subtable Case 1A Case 1B Case 1C Case 2A Case 2B Case 3A Case 3B

Combining in Data Entry Form Main form holds main table data Main form holds main table data form displays one main record at a time form displays one main record at a time Embedded subforms hold subtable data Embedded subforms hold subtable data form displays multiple records in datasheet view form displays multiple records in datasheet view Lookup table embedded on form Lookup table embedded on form as a dropdown box or scrolling list as a dropdown box or scrolling list view the code names on the list view the code names on the list click on choice and CODE is entered on record click on choice and CODE is entered on record May be entered on main table or a subtable May be entered on main table or a subtable

Where Lookup Code Data Goes If the lookup is a code for something that occurs ONCE per record, it goes into a field on that record. If the lookup is a code for something that occurs ONCE per record, it goes into a field on that record. If the lookup information could occur more than once you have some choices. If the lookup information could occur more than once you have some choices. create a fixed number of fields, each with the same lookup and some way to order them create a fixed number of fields, each with the same lookup and some way to order them create a collection sub-table that can accept multiple rows of data, including the lookup code in each row, linked to one record. create a collection sub-table that can accept multiple rows of data, including the lookup code in each row, linked to one record.