access queries office 2013/365 1. queries most common type of query is selection(projection) specify...
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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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• 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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Resulting Dynaset
SQLSELECT Customers.[ID], Customers.[Last Name], Customers.[First Name], Customers.[E-mail Address], Customers.[Job Title], Customers.[Business Phone]FROM Customers;
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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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
Resulting Dynaset
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SQLSELECT Customers.ID, Customers.Company, Customers.CityFROM CustomersWHERE (((Customers.City)="Los Angelas") AND ((Customers.[State/Province])="CA"));
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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
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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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