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CURS7 - Excel Databases
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1
Managing Excel Databases
Validating Data Entry
Filtering a Database (Using the AutoFilter
and the Advanced Filter Commands)
Using Functions to Extract Details from a
List (Database Statistical Functions)
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Excel Databases. Validating Data Entry
Validation represents a procedure that allows the verification to
the correctness of data entry into the cells. This procedure is
operational for any worksheet cell that contains values edited by
the user. Through validation data entry one restrict the entries
into the cells according to a given criteria at which the worksheet
values, entered by the user, must to respond.
An important aspect concerning this facility of databases
exploitation is that the validation is not operational at all as
concerns an Excel formula because one considers that any
formula returns automatically the correct results.
In fact, the validation of data entry presumes the following steps:
Select the range of cells where you want the validation to apply;
Choose Validation command from the Data menu – Excel will
display the Data Validation dialog box.
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Validating Data Entry Specifying Data Type and Acceptable Values
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In Data Validation dialog box we choose firstly the Settings tab
that allows us to set up the validation rules for the selected cells.
To specify the kind of data we’ll allow, we must open the Allow
list from where we can choose one of the following data type:
Whole number, Decimal number, List, Date an Time, Text length
and Custom. Initially, Excel allows us to enter into its worksheet
cells any kind of data, and that because the default option from
this list is actually “Any value”, so, the data entries are made
without any restrictions.
The dialog box has also a second drop-down list that contains all
the comparison operators (between, not between, equal to and
the like). After we choose the suitable operator, Excel modifies
the informational structure of the dialog box, so that we can enter
all the additional information about the chosen type.
For example, if we choose the Whole number option and
Between operator, the dialog box will specify both a minimum
and maximum acceptable value.
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Validating Data Entry Specifying Data Type and Acceptable Value
The range “Personal Numeric Code” will be validated so
that to admit only a number with 13 digits.
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Validating Data Entry
Specifying an Input Message
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To supply an input prompt to guide us when we are entering a data
into the current cell, we simply click the Input Message tab in the
Data Validation dialog box.
Through this facility we have the opportunity to specify both the
content of the custom message and the title of the text box in
which it’s displayed our message. The title automatically formatted
using the bold characters.
This user’s custom message will be displayed as a comment
beside the validated cell whenever the user selects that cell.
So, that prompt will appear whenever the validated cell is active.
For example, we can have a prompt which specifies that the cell
requires an integer number with 13 digits.
By choosing Data Validation we can create such an input
message, even without creating a validation rule, in other words,
without forcing the user to enter a particular kinds of values.
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Validating Data Entry Specifying Error Alert Style and Message
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Validating Data Entry Specifying Error Alert Style and Message
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If we somehow elude the validation rule when we are entering a
data into the current cell, Excel will display a standard error
message pointing out that the value we entered into that cell is
not a valid one.
Through a dialog box, Excel actually forces the user either to retry
the entry using a correct value this time, or to cancel the action
and leaves this way the previous value in place (or leaves the
cell empty).
If we want to set up a custom error message when the entry is
invalid we have to use the third tab, that is the Error Alert tab.
Through this facility one can establish:
1. First of all the window title
2. Then the proper error message of the user
3. And, finally, we choose the style of message that appears
when the user doesn’t respect the validation rule.
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These three message styles display different icons in the dialog
box and also they have different consequences for the user during
an invalid entry.
If our message style is Stop (actually the default option), the user
is practically forced to Retry or even to Cancel the action.
If we choose the option Warning the entry is invalid but however
the user have a chance to leave the wrong value into the current
cell simply by choosing the answer Yes. The button No allows to
reenter an other value that could be a correct one.
If we choose Information the user will be told about the produced
error, but will not be given a retry option (we can only to accept
the invalid value through Ok or even to Cancel the action).
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Validating Data Entry. Examples
The list of data types that appears on the Settings tab doesn’t
include a Text type. How can we force a text entry into the cells of
the Excel worksheet?
Taking into account that the Text Length option doesn’t create a
requirement for a text entry, however, to require text, we must
choose the Custom option that allow to type in the custom formula,
actually, the address of the selected cell (B3 in this instance).
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Filtering a Database
To filter a worksheet database means to hide all the
database records, except those that satisfy the conditions
specified into a criteria range.
From the complexity criteria standpoint, Excel provides
two filtering commands:
AutoFilter for simple criteria;
Advanced Filter for more complex criteria and also
to extract a subset of our database to another
location of the worksheet.
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Filtering a Database. AutoFilter command
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Filtering a Database. AutoFilter command
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Suppose that we have a database which manage the employees’
informational structure, comprising the fields: Personal Numeric
Code, Employee’s name, Department and the other heading labels.
Starting from this initial structure we intend to filter this database,
using the AutoFilter facility, with the purpose to extract only those
database records in which the employees’ department is IT.
To use the AutoFilter command, firstly we select any cell in the
database, then we choose from the Data menu, the Filter
command and, after that, the AutoFilter option.
Excel will display drop-down arrows next to each of the column
headings of our database. Next, we can simply click the arrow of
the department heading to reveal the list that contains all the
departments, as unique values. From this list we select the IT
department that represents in fact the filtering criteria.
As result, Excel will display a restricted structure of the database
that comprises only the records which meet the specified criteria,
hiding actually the other records (the other rows of the table).
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Filtering a Database. AutoFilter command
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We can also define a requirement that presumes two selecting
conditions. Suppose, for instance, that we want to display a list
containing all the employees which are working on in IT and
Creditare company’s departments.
To specify more criteria to a single column (Department) we have
to use the Custom option from the drop-down list of that field.
In the Custom AutoFilter dialog box one can specify two
conditions, using two possible logical operators which are And,Or.
The list boxes on the left side of the dialog box provide a selection
of relationships (Equals, Does Not Equal, Is Greater Than and so
on), and the list boxes on the right side allow us to select the
values that appear in Department column.
The resulting list will contain only the records that meet the
specified criteria, hiding the other ones.
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In contrast to the AutoFilter command, the Advanced Filter
command allows to do the following:
Specify criteria involving two or even more columns and the
logical operators;
Specify three or more criteria for a particular column, where at
least one OR logical operator is involved;
Specify computed criteria where we can enter an Excel function.
In addition, the Advanced Filter command can be used to extract
the records from the database, placing copies of those records in
another location of the current worksheet.
To filter a database using this facility we must choose the
Advanced Filter option, from the Filter command list, from the
Data menu.
Using the ADVANCED FILTER Command
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Using the ADVANCED FILTER Command
Database
address
Criteria
range
Possibilities
for displaying
the filter
results
Resulting
range
Displaying
records with
unique value
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Database Functions
General Syntax:
=function_name(database;field;criteria)
DSUM
DPRODUCT
DMIN
DMAX
DAVERAGE
DCOUNT(A)
DGET
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The Database statistical functions represents in fact counterparts
of the well-known mathematical and statistical functions (SUM,
PRODUCT, COUNT, MIN, MAX, AVERAGE), excepting the
function DGET which has not a corresponding function.
The difference between these database functions and their
counterparts is that the formers operate only for the database
records that match the conditions specified in the criteria range.
DSUM adds the values
DPRODUCT multiplies the values
DMIN returns the smallest number
DMAX returns the largest number
DAVERAGE calculates the average value
DCOUNT and DCOUNTA counts the cells that contain either only
numbers (DCOUNT), or any kind of data (DCOUNTA)
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All these functions execute some calculations, but only
for those records of a database that perfectly match
with the given conditions.
DGET extracts an information from a database, the information
that satisfies the required condition specified into criteria range.
What means the database functions arguments:
Database – represent either the address of the worksheet
database which contains in the first row the database labels, or a
range name of the database;
Field – indicates which database column is used in the function
for the wished calculation operation (either using the column
label, or using the number of the column within the database);
Criteria – represents a range of cells that contains the condition
or the conditions that must be satisfied.
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