Package org.apache.torque.util.functions
Class AggregateFunction
- java.lang.Object
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- org.apache.torque.util.functions.AggregateFunction
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- All Implemented Interfaces:
Column
,SQLFunction
public class AggregateFunction extends Object implements SQLFunction
A container for classes that will generate SQL for the SQL99 Standard Aggregate functions. These can be used via the Criteria.addSelectColumn method to produce SQL statements that can be called via the BasePeerImpl.doSelect methods.
Note database servers that use non-standard function names can be supported by setting the function name in the constructor accordingly.
E.g., older MySQL servers use LEAST instead of MIN. This can be supported by supplying "LEAST" as function name.
- Version:
- $Id: AggregateFunction.java 1867515 2019-09-25 15:02:03Z gk $
- Author:
- Greg Monroe
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Constructor Summary
Constructors Modifier Constructor Description protected
AggregateFunction(String function, Column column, boolean distinct)
Constructor for aggregate functions.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description Object
getArgument(int i)
Returns the function parameters at index i.Object[]
getArguments()
Return all the parameters as an object array.Column
getColumn()
Returns the column the function is applied to.String
getColumnName()
Returns the column name.String
getFullTableName()
Returns the table name prefixed with the schema name if it exists.protected String
getFunction()
Get the function name to use, e.g.String
getSchemaName()
Returns the name of any fixed schema prefix for the column's table (if any).String
getSqlExpression()
Generate the SQL for this function.String
getTableName()
Returns the name of the associated table (not prefixed by the schema name).boolean
isDistinct()
Should the column have DISTINCT added in front of it?void
setArguments(Object... args)
Assumes that there are one or two arguments being specified.void
setColumn(Column column)
Sets the column the function is applied to.void
setFunction(String function)
Set the function name to use, e.g.
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Constructor Detail
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AggregateFunction
protected AggregateFunction(String function, Column column, boolean distinct)
Constructor for aggregate functions.- Parameters:
function
- the function name, not null or blank.column
- the column to apply the function to, not null.distinct
- whether to apply DISTINCT to the column.
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Method Detail
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getColumn
public Column getColumn()
Returns the column the function is applied to.- Specified by:
getColumn
in interfaceSQLFunction
- Returns:
- the column, not null.
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setColumn
public void setColumn(Column column)
Sets the column the function is applied to.- Parameters:
column
- the column, not null.
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isDistinct
public boolean isDistinct()
Should the column have DISTINCT added in front of it?- Returns:
- True if DISTINCT is needed.
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getFunction
protected String getFunction()
Get the function name to use, e.g. AVG, MIN, LEAST.- Returns:
- The function name.
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setFunction
public void setFunction(String function)
Set the function name to use, e.g. AVG, MIN, LEAST.- Parameters:
function
- The function name to use, not null or blank.- Throws:
UnsupportedOperationException
- if a subclass does not support changing the function name; never thrown by this implementation.
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getSqlExpression
public String getSqlExpression()
Generate the SQL for this function.- Specified by:
getSqlExpression
in interfaceColumn
- Returns:
- the SQL expression for the column, not null.
- Throws:
IllegalStateException
- if the arguments are not set
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getArgument
public Object getArgument(int i)
Description copied from interface:SQLFunction
Returns the function parameters at index i. Should be null if parameter does not exist.- Specified by:
getArgument
in interfaceSQLFunction
- Parameters:
i
- The 0 based parameter to get.- Returns:
- The parameter. Null if one does not exist.
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getArguments
public Object[] getArguments()
Description copied from interface:SQLFunction
Return all the parameters as an object array. This allow for processing of the parameters in their original format rather than just in String format. E.g. a parameter might be specified as a Date object, or a Column object.- Specified by:
getArguments
in interfaceSQLFunction
- Returns:
- Should return a valid Object array and not null. E.g. implementors should return new Object[0] if there are no parameters.
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setArguments
public void setArguments(Object... args)
Assumes that there are one or two arguments being specified. The first being a column identifier, and the second being an optional boolean indicating if DISTINCT needs to be added.- Specified by:
setArguments
in interfaceSQLFunction
- Parameters:
args
- The column to apply the function to.- Throws:
IllegalArgumentException
- If at least one argument has not been supplied or the second argument object is not Boolean.
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getColumnName
public String getColumnName()
Returns the column name. This implementation always return null because we do not reference a real column.- Specified by:
getColumnName
in interfaceColumn
- Returns:
- the column name, always null.
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getTableName
public String getTableName()
Description copied from interface:Column
Returns the name of the associated table (not prefixed by the schema name).- Specified by:
getTableName
in interfaceColumn
- Returns:
- the name of the table, may be null but not blank.
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getSchemaName
public String getSchemaName()
Description copied from interface:Column
Returns the name of any fixed schema prefix for the column's table (if any).- Specified by:
getSchemaName
in interfaceColumn
- Returns:
- the schema name, or null if the schema is not known.
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getFullTableName
public String getFullTableName()
Description copied from interface:Column
Returns the table name prefixed with the schema name if it exists. I.e. if a schema name exists, the result will be schemaName.tableName, and otherwise it will just be tableName.- Specified by:
getFullTableName
in interfaceColumn
- Returns:
- the fully qualified table name of the column, may be null but not blank.
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