Thread: [GENERAL] Syntax error needs fresh eyeballs
My schema includes three tables and psql throws an error I'm not seeing when I try to read the schema into the database. I'd appreciate fresh eyes looking at the table and learning what error I'm not seeing. The tables: CREATE TABLE Weather ( site_id INTEGER PRIMARY KEY, site_name TEXT, site_location TEXT ); CREATE TABLE Weather_Params ( site_id INTEGER REFERENCES Weather(site_id), param TEXT, param_unit TEXT, freq INTEGER, freq_unit TEXT, equip TEXT, PRIMARY KEY (site_id, param) ); CREATE TABLE Weather_Data ( site_id INTEGER REFERENCES Weather(site_id), monit_date DATE, monit_time TIME, read_by TEXT, -- name of employee collecting data param TEXT REFERENCES Weather_Params(param), param_value REAL, PRIMARY KEY (site_id, monit_date, monit_time, param) ); The error: ERROR: there is no unique constraint matching given keys for referenced table "weather_params". TIA, Rich
Rich Shepard <rshepard@appl-ecosys.com> writes: > My schema includes three tables and psql throws an error I'm not seeing > when I try to read the schema into the database. I'd appreciate fresh eyes > looking at the table and learning what error I'm not seeing. Hm, seems straightforward enough to me: the only uniqueness constraint you've got in Weather_Params is > PRIMARY KEY (site_id, param) but in Weather_Data you write > param TEXT > REFERENCES Weather_Params(param), so you get this > ERROR: there is no unique constraint matching given keys for referenced > table "weather_params". because Weather_Params.param isn't constrained to be unique. Weather_Params' pkey constrains the combination of site_id and param to be unique, but that doesn't make param alone unique, so param in Weather_Data isn't enough to reference a well-defined row of Weather_Params. Seeing that Weather_Data also has a site_id column, I'm going to guess that what you wanted to put in Weather_Data is a two-column FK: FOREIGN KEY (site_id, param) REFERENCES Weather_Params (site_id, param) That would match Weather_Params' pkey, so it's enough to identify a unique row of Weather_Params. regards, tom lane
From: Rich Shepard
My schema includes three tables and psql throws an error I'm not seeing when I try to read the schema into the database. I'd appreciate fresh eyes looking at the table and learning what error I'm not seeing.
The tables:
CREATE TABLE Weather (
site_id INTEGER PRIMARY KEY,
site_name TEXT,
site_location TEXT
);
CREATE TABLE Weather_Params (
site_id INTEGER
REFERENCES Weather(site_id),
param TEXT,
param_unit TEXT,
freq INTEGER,
freq_unit TEXT,
equip TEXT,
PRIMARY KEY (site_id, param)
);
CREATE TABLE Weather_Data (
site_id INTEGER
REFERENCES Weather(site_id),
monit_date DATE,
monit_time TIME,
read_by TEXT, -- name of employee collecting data
param TEXT
REFERENCES Weather_Params(param),
param_value REAL,
PRIMARY KEY (site_id, monit_date, monit_time, param) );
The error: ERROR: there is no unique constraint matching given keys for referenced table "weather_params".
-----------------------
Just a guess...You've camel-cased the table names but aren't using double quotes. Try either lower-casing all table names and references to them, or double-quoting all identifiers.
Mike
On Mon, 26 Dec 2016, Tom Lane wrote: >> ERROR: there is no unique constraint matching given keys for referenced >> table "weather_params". > > because Weather_Params.param isn't constrained to be unique. ... > Seeing that Weather_Data also has a site_id column, I'm going to guess > that what you wanted to put in Weather_Data is a two-column FK: > > FOREIGN KEY (site_id, param) REFERENCES Weather_Params (site_id, param) > > That would match Weather_Params' pkey, so it's enough to identify a > unique row of Weather_Params. Thanks, Tom. Yes, I do want a 2-column FK. Much appreciated, Rich