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ITN270 Advanced Internet DatabasesLecture 11. The Perl DBI API - Part II

•Topics:– Perl DBI interface to MySQL

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Related issues for DBI with MySQL

• Handling Queries That Return a Results Set– Working with complete Sets

• use matrix contains to contain all the information

• Example:

– fetchrow_array ()

– fetchrow_arrayref()

– selectall_arrayref($query);

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Using fetchrow_array ()• Example:

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Using fetchall_arrayref()

• Example:

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Using selectall_arrayref($query)

• Example:

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Checking for NULL values

• Example:if (!defined ($col_val)) {print "NULL\n";}

elsif ($col_val eq " ") {print "empty string\n”;}

elsif ($col_val == 0) {print "zero\n";}

else { print "other\n";}

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Quoting Issues

• Example:– Double Quotes vs. Single Quotes

• “SELECT * FROM member WHERE id = $var”

• ‘SELECT * FROM member WHERE id = $var’

– Using qq{ }, qq( ), or qq/ /• $date = “2002-09-16”;

• $date = qq{2002-09-16};

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Binding Query Results To Script Variable

• It allows to parameterized the output by retrieving column values into variable automatially when fetching a row with out having to assign values to the variables yourself

• Example:

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Using DBI in Web Application

• Example: Connection

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Using DBI in Web Application

• Example: Issue Query

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Using DBI in Web Application

• Example: Read & Display data

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Using DBI in Web Application

• Example: Close the connection