How to create relation between nodes grouped under labels in neo4j?

Question

I had created two group of nodes in graph using the following cypher query

pharma group

CREATE ( p1:pharma { name: " Magnesium ", id: " 12 " } ) 
CREATE ( p2:pharma { name: " Hyoscine Butylbromide ", id: " 22 " } ) 
CREATE ( p3:pharma { name: " Propantheline Bromide ", id: " 23 ",  } );

ind group

CREATE ( i1:ind { id: '1', name: 'Dyspepsia',  pdfk: '12'}) 
CREATE ( i2:ind { id: '5', name: 'Symptomic relief of intestinal disorder', pdfk: '22'}) 
CREATE ( i3:ind { id: '6', name: 'Symptomic relief of disorder', pdfk: '22'}) 
CREATE ( i4:ind { id: '7', name: 'Bowel colic', review: 'False', pdfk: '23'});

its just like relational database tabels, Now I want to define relation ship between these two group of nodes..

relationship like = node in pharma with id 12 has a relationship name HAS_IND with node in ind with id 1 ?

somewhere like this

MATCH (a:pharma),(b:ind)
WHERE a.id = '12' AND b.id = '1'
CREATE (a)-[:has_ind]->(b);

I tried these too

MATCH (a:pharmaDrug),(b:indication)
WHERE a.name = 'Magnesium Carbonate' AND b.name = 'Dyspepsia'
CREATE (a)-[:has_indication]->(b);

but both are giving Returned 0 rows in 530 ms in the console ?

Please help me to find the correct cypher query for this purpose. Thanks in advance.

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My changes are as follows

CREATE ( p1:pharma { name: "Magnesium", id: 12 } ) 
CREATE ( p2:pharma { name: "Hyoscine Butylbromide", id: 22 } ) 
CREATE ( p3:pharma { name: "Propantheline Bromide", id: 23 } );




CREATE ( i1:ind { id: 1, name: 'Dyspepsia',  pdfk: '12'}) 
CREATE ( i2:ind { id: 5, name: 'Symptomic relief of intestinal disorder', pdfk: '22'}) 
CREATE ( i3:ind { id: 6, name: 'Symptomic relief of disorder', pdfk: '22'}) 
CREATE ( i4:ind { id: 7, name: 'Bowel colic', review: 'False', pdfk: '23'});

this create nodes under two labels

MATCH (a:pharma),(b:ind)
WHERE a.id = ' 12 ' AND b.id = ' 1 '
CREATE (a)-[:has_indication]->(b);

this give zero rows affected with no output ?

Answer 1

It's because of the way you've created your items, if you look at your 'pharma' code you have:

CREATE ( p1:pharma { name: " Magnesium ", id: " 12 " } )

To match against this you need to do:

MATCH (a:pharma) 
WHERE a.id = ' 12 '
RETURN a

I've added extra spaces around the '12' to get it to match. So you're query would read as:

MATCH (a:pharma),(b:ind)
WHERE a.id = ' 12 ' AND b.id = '1'
CREATE (a)-[:has_indication]->(b)

Now, that'll get it to work - but it might be worth changing your model a bit, if the id is always an integer, I would change your creates to being:

CREATE ( p1:pharma { name: "Magnesium", id: 12 } ) 
CREATE ( p2:pharma { name: "Hyoscine Butylbromide", id: 22 } ) 
CREATE ( p3:pharma { name: "Propantheline Bromide", id: 23 } );

and be SUPER careful with your use of the " (or ') character, in your original creates you are adding extra spaces for the names as well (which is why your second query didn't work)

EDIT

OK, this is a fully working set of data, I've edited both of your create statements to get this:

CREATE ( p1:pharma { name: 'Magnesium', id: 12 } ) 
CREATE ( p2:pharma { name: 'Hyoscine Butylbromide', id: 22 } ) 
CREATE ( p3:pharma { name: 'Propantheline Bromide', id: 23} )
CREATE ( i1:ind { id: 1, name: 'Dyspepsia',  pdfk: 12}) 
CREATE ( i2:ind { id: 5, name: 'Symptomic relief of intestinal disorder', pdfk: 22}) 
CREATE ( i3:ind { id: 6, name: 'Symptomic relief of disorder', pdfk: 22}) 
CREATE ( i4:ind { id: 7, name: 'Bowel colic', review: 'False', pdfk: 23})

Basically I've removed the ' characters and used integers for id (and pdfk). The MATCH for this is:

MATCH (a:pharma),(b:ind)
WHERE a.id = 12 AND b.id = 1
CREATE (a)-[:has_ind]->(b)

And to check it works (aside from the message you get back):

MATCH (p:pharma),(i:ind) RETURN p,i

You'll see one is linked to another.