NAME

DBIx::MyParse::Item - Accessing the items from a DBIx::MyParse parse tree

SYNOPSIS

        use DBIx::MyParse;
        use DBIx::MyParse::Query;
        use DBIx::MyParse::Item;

        my $parser = DBIx::MyParse->new();
        my $query = $parser->parse("SELECT field_name FROM table_name");
        my $item_list = $query->getSelectItems();
        my $first_item = $item_list->[0];
        print $first_item->getType();           # Prints "FIELD_ITEM"
        print $first_item->getFieldName()       # Prints "field_name"
        

DESCRIPTION

MySQL uses a few dozen Item objects to store the various nodes possible in a parse tree. For the sake of simplicity, we only use a single object interface in Perl to access things.

METHODS

my $item_type = $item->getType();

This returns the type of the Item as a string, to facilitate dumping and debugging.

        if ($item_type eq 'FIELD_ITEM') { ... } # Correct
        if ($item_type == FIELD_ITEM) { ... }   # Will not work

The possible values are listed in enum Type in sql/item.h in the MySQL source.

        enum Type {FIELD_ITEM, FUNC_ITEM, SUM_FUNC_ITEM, STRING_ITEM,
                INT_ITEM, REAL_ITEM, NULL_ITEM, VARBIN_ITEM,
                COPY_STR_ITEM, FIELD_AVG_ITEM, DEFAULT_VALUE_ITEM,
                PROC_ITEM,COND_ITEM, REF_ITEM, FIELD_STD_ITEM,
                FIELD_VARIANCE_ITEM, INSERT_VALUE_ITEM,
                SUBSELECT_ITEM, ROW_ITEM, CACHE_ITEM, TYPE_HOLDER,
                PARAM_ITEM
        };

From those, the following are explicitly supported:

        FIELD_ITEM, FUNC_ITEM, SUM_FUNC_ITEM,
        STRING_ITEM, INT_ITEM, REAL_ITEM, NULL_ITEM, VARBIN_ITEM
        REF_ITEM, COND_ITEM

In addition, DBIx::MyParse defines its own TABLE_ITEM in case a table, rather than a field, is being referenced.

REF_ITEM is a FIELD_ITEM that is used in a HAVING clause. VARBIN_ITEM is created when a Hex value is passed to MySQL (e.g. 0x5061756c).

my $func_type = $item->getFuncType();

if $item->getType() eq "FUNC_ITEM", you can call getFuncType() to determine what type of function it is. For MySQL, all operators are also of type FUNC_ITEM.

The possible values are again strings (see above) and are listed in sql/item_func.h under enum Functype

        enum Functype {
                UNKNOWN_FUNC,EQ_FUNC,EQUAL_FUNC,NE_FUNC,LT_FUNC,LE_FUNC,
                GE_FUNC,GT_FUNC,FT_FUNC,
                LIKE_FUNC,NOTLIKE_FUNC,ISNULL_FUNC,ISNOTNULL_FUNC,
                COND_AND_FUNC, COND_OR_FUNC, COND_XOR_FUNC, BETWEEN, IN_FUNC,
                INTERVAL_FUNC, ISNOTNULLTEST_FUNC,
                SP_EQUALS_FUNC, SP_DISJOINT_FUNC,SP_INTERSECTS_FUNC,
                SP_TOUCHES_FUNC,SP_CROSSES_FUNC,SP_WITHIN_FUNC,
                SP_CONTAINS_FUNC,SP_OVERLAPS_FUNC,
                SP_STARTPOINT,SP_ENDPOINT,SP_EXTERIORRING,
                SP_POINTN,SP_GEOMETRYN,SP_INTERIORRINGN,
                NOT_FUNC, NOT_ALL_FUNC, NOW_FUNC, VAR_VALUE_FUNC
        };

if $item->getType() eq "SUM_FUNC_ITEM", $item->getFuncType() can be any of the aggregate functions listed in enum Sumfunctype in sql/item_sum.h:

        enum Sumfunctype { COUNT_FUNC,COUNT_DISTINCT_FUNC,SUM_FUNC,AVG_FUNC,MIN_FUNC,
                MAX_FUNC, UNIQUE_USERS_FUNC,STD_FUNC,VARIANCE_FUNC,SUM_BIT_FUNC,
                UDF_SUM_FUNC, GROUP_CONCAT_FUNC
        };

For MySQL, all functions not specifically listed above are UNKNOWN_FUNC and you must call getFuncName().

my $func_name = $item->getFuncName();

Returns the name of the function called, such as "concat_ws", "md5", etc. If $item is not a function, but an operator, the symbol of the operator is returned, such as "+", "||", etc. The name of the function will be lowercase regardless of the orginal case in the SQL string.

my $arguments_ref = $item->getArguments();

Returns a reference to an array containing all the arguments to the function/operator. Each item from the array is also an DBIx::MyParse::Item object, even if it is a simple string or a field name.

my $database_name = $item->getDatabaseName();

if $item is FIELD_ITEM, REF_ITEM or a TABLE_ITEM, getDatabaseName() returns the database the field belongs to, if it was explicitly specified. If it was not specified explicitly, such as was given previously with a "USE DATABASE" command, getDatabaseName() will return undef. This may change in the future if we incorporate some more of MySQL's logic

my $table_name = $item->getTableName();

Returns the name of the table for a FIELD_ITEM or TABLE_ITEM object. For FIELD_ITEM, the table name must be explicitly specified with "table_name.field_name" notation. Otherwise returns undef and does not attempt to guess the name of the table.

my $field_name = $item->getTableName();

Returns the name of the field for a FIELD_ITEM object.

my $value = $item->getValue();

Returns, as string, the value of STRING_ITEM, INT_ITEM, REAL_ITEM and VARBIN_ITEM objects.

my $direction = $item->getOrderDir(); =item my $direction = $item->getGroupDir();

For an FIELD_ITEM used in GROUP BY or ORDER BY, those two identical functions return either the string "ASC" or the string "DESC" depending on the group/ordering direction. Default is "ASC" and will be returned even if the query does not specify a direction.

my $alias = $item->getAlias();

Returns the name of the Item if provided with an AS clause, such as SELECT field AS alias.