write this in PSQL ,

schema create table teams (tid varchar(30), location varchar(30), name varchar(30),league varchar(30), primary key (tid, league));

create table coaches_season (cid varchar(30), year int, yr_order int,firstname varchar(30), lastname varchar(30), season_win int, season_loss int,playoff_win int, playoff_loss int, tid varchar(30), primary key (cid, year,yr_order));

create table draft (draft_year int, draft_round int, selection int, tidvarchar(30), firstname varchar(30), lastname varchar(30), ilkid varchar(30),draft_from varchar(100), league varchar(30));

create table players (ilkid varchar(30), firstname varchar(30), lastnamevarchar(30), position varchar(1), first_season int, last_season int, h_feet int,h_inches real, weight real, college varchar(100), birthday varchar(30), primarykey (ilkid));

create table player_rs_career (ilkid varchar(30), firstname varchar(30),lastname varchar(30), league varchar(10), gp int, minutes int, pts int, drebint, oreb int, reb int, asts int, stl int, blk int, turnover int, pf int, fgaint, fgm int, fta int, ftm int, tpa int, tpm int);

create table player_rs (ilkid varchar(30), year int, firstname varchar(30),lastname varchar(30), tid varchar(30), league varchar(10), gp int, minutes int,pts int, dreb int, oreb int, reb int, asts int, stl int, blk int, turnover int,pf int, fga int, fgm int, fta int, ftm int, tpa int, tpm int, primary key(ilkid,year, tid));

2. Write a function named player_weight_var that, given a team ID (as the 1st parameter) and a year (as the 2nd parameter), returns the variance (as a floating number) of the weights of all players played in that team in the given season. Note that, as a basic statistical measure of a set of numbers, the variance is defined as the average of the squared differences from the mean. If you do not find any information about the given team and year combination, your function should return -1.0.