Some stuff I learned.

Postgres is statically typed

finance_service=# select count(*) from "Purchases" WHERE echpro = 0;                        
ERROR:  operator does not exist: character varying = integer
LINE 1: select count(*) from "Purchases" WHERE echpro = 0;
                                                      ^
HINT:  No operator matches the given name and argument type(s). You might need to add explicit type casts.
  					

The operator has to match the type

finance_service=# select count(*) from "Purchases" WHERE echpro = CAST('0' as VarChar);  
 count 
-------
    54
(1 row)
              					

Table names get converted to lowercase

finance_service=# \d Purchases
Did not find any relation named "Purchases".
  					

Surround mixed case with quotes

finance_service=# \d "Purchases"
                                       Table "public.Purchases"
     Column     |           Type           |                        Modifiers                         
----------------+--------------------------+----------------------------------------------------------
 id             | integer                  | not null default nextval('"Purchases_id_seq"'::regclass)
 createdAt      | timestamp with time zone | 
 updatedAt      | timestamp with time zone | 
 deletedAt      | timestamp with time zone | 
 deal_date      | timestamp with time zone | 
 deal_number    | character varying(255)   | 
 model          | character varying(255)   | 
 salesperson_id | character varying(255)   | 
 ProfileId      | character varying(255)   | 
 tftpro         | character varying(255)   | 
 echpro         | character varying(255)   | 
 fabpro         | character varying(255)   | 
 extpro         | character varying(255)   | 
 svcpro         | character varying(255)   | 
 tireshldpro    | character varying(255)   | 
 tyronpro       | character varying(255)   | 
 location       | character varying(255)   | 
 product_sku    | character varying(255)   | 
 secondary      | boolean                  | 
Indexes:
    "Purchases_pkey" PRIMARY KEY, btree (id)
  					

Lots of slash commands

finance_service=# \?
General
  \copyright             show PostgreSQL usage and distribution terms
  \g [FILE] or ;         execute query (and send results to file or |pipe)
  \gset [PREFIX]         execute query and store results in psql variables
  \q                     quit psql
  \watch [SEC]           execute query every SEC seconds

Help
  \? [commands]          show help on backslash commands
  \? options             show help on psql command-line options
  \? variables           show help on special variables
  \h [NAME]              help on syntax of SQL commands, * for all commands

Query Buffer
  \e [FILE] [LINE]       edit the query buffer (or file) with external editor
  \ef [FUNCNAME [LINE]]  edit function definition with external editor
  \p                     show the contents of the query buffer
  \r                     reset (clear) the query buffer
  \s [FILE]              display history or save it to file
  \w FILE                write query buffer to file

Input/Output
  \copy ...              perform SQL COPY with data stream to the client host
  \echo [STRING]         write string to standard output
  \i FILE                execute commands from file
  \ir FILE               as \i, but relative to location of current script
  \o [FILE]              send all query results to file or |pipe
  \qecho [STRING]        write string to query output stream (see \o)

Informational
  (options: S = show system objects, + = additional detail)
  \d[S+]                 list tables, views, and sequences
  \d[S+]  NAME           describe table, view, sequence, or index
  \da[S]  [PATTERN]      list aggregates
  \db[+]  [PATTERN]      list tablespaces
  \dc[S+] [PATTERN]      list conversions
  \dC[+]  [PATTERN]      list casts
  \dd[S]  [PATTERN]      show object descriptions not displayed elsewhere
  \ddp    [PATTERN]      list default privileges
  \dD[S+] [PATTERN]      list domains
  \det[+] [PATTERN]      list foreign tables
  \des[+] [PATTERN]      list foreign servers
  \deu[+] [PATTERN]      list user mappings
  \dew[+] [PATTERN]      list foreign-data wrappers
  \df[antw][S+] [PATRN]  list [only agg/normal/trigger/window] functions
  \dF[+]  [PATTERN]      list text search configurations
  \dFd[+] [PATTERN]      list text search dictionaries
  \dFp[+] [PATTERN]      list text search parsers
  \dFt[+] [PATTERN]      list text search templates
  \dg[+]  [PATTERN]      list roles
  \di[S+] [PATTERN]      list indexes
  \dl                    list large objects, same as \lo_list
  \dL[S+] [PATTERN]      list procedural languages
  \dm[S+] [PATTERN]      list materialized views
  \dn[S+] [PATTERN]      list schemas
  \do[S]  [PATTERN]      list operators
  \dO[S+] [PATTERN]      list collations
  \dp     [PATTERN]      list table, view, and sequence access privileges
  \drds [PATRN1 [PATRN2]] list per-database role settings
  \ds[S+] [PATTERN]      list sequences
  \dt[S+] [PATTERN]      list tables
  \dT[S+] [PATTERN]      list data types
  \du[+]  [PATTERN]      list roles
  \dv[S+] [PATTERN]      list views
  \dE[S+] [PATTERN]      list foreign tables
  \dx[+]  [PATTERN]      list extensions
  \dy     [PATTERN]      list event triggers
  \l[+]   [PATTERN]      list databases
  \sf[+] FUNCNAME        show a functions definition
  \z      [PATTERN]      same as \dp

  					

Can I get a GUI please?

https://eggerapps.at/postico/