Access Queries

Access Queries

Office 2013/365

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Queries

• Most common type of Query is selection(projection)• Specify sources for data retrieval

• table(s) and/or query(ies)

• Specify attributes(fields) to be retrieved• Selection criteria• Calculations that need to be performed

• Action Queries• Other types such as crosstabs

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Query Creation

• Structured Query Language (SQL)• The user enters commands according to a pre-

defined syntax to retrieve desired data. • Query By Example (QBE)

• The user starts with a sample of the table(s) columns and marks the fields he or she wants to include in the answer.

• Defaults are available for summarizing and manipulating the data.

Creating Queries

• Query Wizard • QBE Query Design

• The user starts with a sample of the table(s) columns and marks the fields he or she wants to include in the answer.

• Defaults are available for summarizing and manipulating the data.

• SQL design (beyond scope of our class)• The user enters commands according to a pre-defined

syntax to retrieve desired data.

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Creating Query• Wizards

• Click on create tab • Select query wizard • Select simple query• Select your data source(s)• Select desired attributes from each data source• Select next• Name query• Click on finish

• Limitation• May be able to do a summary calculation, but not a

calculated field

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Wizard

Click on create tab and select Query Wizard

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Click on Simple Query wizard

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Select data sources and desired attributes from each source

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Name your query

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Resulting Dynaset

• Access creates the SQL needed to do the query for the wizard

• SQL for previous query example

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SELECT Customers.[ID], Customers.[Last Name], Customers.[First Name], Customers.[E-mail Address], Customers.[Job Title], Customers.[Business Phone]FROM Customers;

Design View• Uses QBE (what we will use)• Design View

• Click on create tab • Select query design• Select your data sources and click on add• Select attributes from each data source and drag

to grid below• Run query• Save query if it will be used on a regular basis

• Can create calculated fields

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Click on create tab and select Query Design

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Select your data sources and click on add

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Select attributes from each data source and double click or drag to grid below

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Select design tab and Click on Run symbol to execute query

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Resulting Dynaset

SQLSELECT Customers.[ID], Customers.[Last Name], Customers.[First Name], Customers.[E-mail Address], Customers.[Job Title], Customers.[Business Phone]FROM Customers;

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Examples to follow based on this

database

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Customer table data

Queries with selection criteria

• Use design view when using selection criteria

• Select your data sources and attributes of interest from your data sources enter selection criteria

• Run query

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Selection Criteria

Query to list Customers from CA

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Resulting Dynaset

SQLSELECT Customers.ID, Customers.Company, Customers.City, Customers.[State/Province]FROM CustomersWHERE (((Customers.[State/Province])="CA"));

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Queries(complex selection criteria)

• Comparison operators • <, • >,• =, • <=,• >=, and • <> Not equal to

• Logical operators• And,• Or, and • Not

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Multiple Criteria

• AND operator• Queries that must satisfy more than one condition,

with all conditions being true, use the AND operator

• OR operator• When any one of several criteria is all that is

required for a row to be displayed in a dynaset, then you use the OR operator

And Operator

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Selection Criteria

Resulting Dynaset

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SQLSELECT Customers.ID, Customers.Company, Customers.CityFROM CustomersWHERE (((Customers.City)="Los Angelas") AND ((Customers.[State/Province])="CA"));

OR Operator

27Selection Criteria

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Resulting Dynaset

SQLSELECT Customers.ID, Customers.Company, Customers.CityFROM CustomersWHERE (((Customers.[State/Province])="CA")) OR (((Customers.[State/Province])="UT"));

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Action queries • Action Queries

• Make table • Append • update • Delete

• Action queries alter information as opposed to selection queries, which passively display information without altering anything

• Back up data before performing action queries• No undo

Action Queries• Make Table

• Query selects records from data base and saves the records in a new table

• Append• Make query add records to an existing table

• Update• Make query update data in an existing table

• Delete• Make the query delete the information from an

existing table where the data matches the criteria

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Action Queries

• Use design view to perform action queries• Select create tab • Query design• Select data source(s)• Select data and/or selection criteria• Select design, select action query• Save query• Run query• You will get a pop-up message indicating what

the query is about to do

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Depending on action query selected you need to specify fields and/or criteria

Make table, Append, Update, Delete

Example Action query message

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Example Action query message

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Append Query Considerations

• Select the table containing the data you want to add• Source may be internal or external

• Select the destination• Fields must be of like data type• Field mapping

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Source Destination

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Note: 1. Access has attempting to map the fields from tblCA to

table customer2. Access maps all fields between the two tables with the

same field names

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Note: 1. Since the two tables used a different names for this field,manual mapping required