FromClause (Esper API Documentation)

java.lang.Object
- com.espertech.esper.client.soda.FromClause

All Implemented Interfaces:

Serializable
```
public class FromClause
extends Object
implements Serializable
```
The from-clause names the streams to select upon.
The most common projected stream is a filter-based stream which is created by FilterStream.
Multiple streams can be joined by adding each stream individually.
Outer joins are also handled by this class. To create an outer join consisting of 2 streams, add one OuterJoinQualifier that defines the outer join relationship between the 2 streams. The outer joins between N streams, add N-1 OuterJoinQualifier qualifiers.

See Also:

Serialized Form

Constructor Summary

Constructors
Constructor and Description
`FromClause()` Ctor.
`FromClause(Stream... streamsList)` Ctor.
`FromClause(Stream streamOne, OuterJoinQualifier outerJoinQualifier, Stream streamTwo)` Ctor for an outer join between two streams.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`FromClause`	`add(OuterJoinQualifier outerJoinQualifier)` Adds an outer join descriptor that defines how the streams are related via outer joins.
`FromClause`	`add(Stream stream)` Adds a stream.
`static FromClause`	`create()` Creates an empty from-clause to which one adds streams via the add methods.
`static FromClause`	`create(Stream... streams)` Creates a from clause that selects from a single stream.
`static FromClause`	`create(Stream stream, OuterJoinQualifier outerJoinQualifier, Stream streamSecond)` Creates a from-clause that lists 2 projected streams joined via outer join.
`List<OuterJoinQualifier>`	`getOuterJoinQualifiers()` Returns the outer join descriptors, if this is an outer join, or an empty list if none of the streams are outer joined.
`List<Stream>`	`getStreams()` Returns the list of streams in the from-clause.
`void`	`setOuterJoinQualifiers(List<OuterJoinQualifier> outerJoinQualifiers)` Set outer joins.
`void`	`setStreams(List<Stream> streams)` Set the streams.
`void`	`toEPL(StringWriter writer, EPStatementFormatter formatter)` Renders the from-clause in textual representation.
`void`	`toEPLOptions(StringWriter writer, EPStatementFormatter formatter, boolean includeFrom)` Renders the from-clause in textual representation.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - FromClause
```
public FromClause()
```
    Ctor.
  - FromClause
```
public FromClause(Stream streamOne,
                  OuterJoinQualifier outerJoinQualifier,
                  Stream streamTwo)
```
    Ctor for an outer join between two streams.
    
    Parameters:
    
    streamOne - first stream in outer join
    
    outerJoinQualifier - type of outer join and fields joined on
    
    streamTwo - second stream in outer join
  - FromClause
```
public FromClause(Stream... streamsList)
```
    Ctor.
    
    Parameters:
    
    streamsList - is zero or more streams in the from-clause.
- Method Detail
  - create
```
public static FromClause create()
```
    Creates an empty from-clause to which one adds streams via the add methods.
    
    Returns:
    
    empty from clause
  - create
```
public static FromClause create(Stream stream,
                                OuterJoinQualifier outerJoinQualifier,
                                Stream streamSecond)
```
    Creates a from-clause that lists 2 projected streams joined via outer join.
    
    Parameters:
    
    stream - first stream in outer join
    
    outerJoinQualifier - qualifies the outer join
    
    streamSecond - second stream in outer join
    
    Returns:
    
    from clause
  - create
```
public static FromClause create(Stream... streams)
```
    Creates a from clause that selects from a single stream.
    Use FilterStream to create filter-based streams to add.
    
    Parameters:
    
    streams - is one or more streams to add to the from clause.
    
    Returns:
    
    from clause
  - add
```
public FromClause add(Stream stream)
```
    Adds a stream.
    Use FilterStream to add filter-based streams.
    
    Parameters:
    
    stream - to add
    
    Returns:
    
    from clause
  - add
```
public FromClause add(OuterJoinQualifier outerJoinQualifier)
```
    Adds an outer join descriptor that defines how the streams are related via outer joins.
    For joining N streams, add N-1 outer join qualifiers.
    
    Parameters:
    
    outerJoinQualifier - is the type of outer join and the fields in the outer join
    
    Returns:
    
    from clause
  - getStreams
```
public List<Stream> getStreams()
```
    Returns the list of streams in the from-clause.
    
    Returns:
    
    list of streams
  - toEPL
```
public void toEPL(StringWriter writer,
                  EPStatementFormatter formatter)
```
    Renders the from-clause in textual representation.
    
    Parameters:
    
    writer - to output to
    
    formatter - for newline-whitespace formatting
  - toEPLOptions
```
public void toEPLOptions(StringWriter writer,
                         EPStatementFormatter formatter,
                         boolean includeFrom)
```
    Renders the from-clause in textual representation.
    
    Parameters:
    
    writer - to output to
    
    includeFrom - flag whether to add the "from" literal
    
    formatter - for newline-whitespace formatting
  - getOuterJoinQualifiers
```
public List<OuterJoinQualifier> getOuterJoinQualifiers()
```
    Returns the outer join descriptors, if this is an outer join, or an empty list if none of the streams are outer joined.
    
    Returns:
    
    list of outer join qualifiers
  - setStreams
```
public void setStreams(List<Stream> streams)
```
    Set the streams.
    
    Parameters:
    
    streams - to set
  - setOuterJoinQualifiers
```
public void setOuterJoinQualifiers(List<OuterJoinQualifier> outerJoinQualifiers)
```
    Set outer joins.
    
    Parameters:
    
    outerJoinQualifiers - to set

Class FromClause

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

FromClause

FromClause

FromClause

Method Detail

create

create

create

add

add

getStreams

toEPL

toEPLOptions

getOuterJoinQualifiers

setStreams

setOuterJoinQualifiers