Select DBeaver

 select customerid

from 

customers 

select cast(customerid as varchar) as customerid_text

from

customers 

select convert(varchar, customerid) as customerid_text

from

customers 

--CONCATENACION--

select concat(customerid,'', customername, '', contactname)

from 

customers

--FUNCIONES DE CADENAS--

--SUBSTRING--

select substring('Microsoft SQL Server', 11, 3) as result;

select customername, substring(customername, 5, 4) as recorte

from

customers

--LEFT Y RIGHT--

select left('Microsoft SQL Server', 9) as result;

select right('Microsoft SQL Server', 6) as result;

select customername, left(customername, 2) as recorte_izq

from

customers

--LENGTH Y DATALENGTH--

select length('Microsoft SQL Server') as result; --En sql server se usa la función length--

select datalength('Microsoft SQL Server') as result; --En sql server se usa la función datalength--

select customername, length(customername) as cantidad_caracteres

from

customers

--CHARINDEX--

select strpos('Microsoft SQL Server', 'SQL') as result; --En sql server se usa la función charindex--

select customername, strpos(customername, 'Imp') as posicion

from

customers

--REPLACE--

select replace('Microsoft SQL Server Hekaton', 'Hekaton', '2014 In-Memory OLTP Engine') as result;

select customername, replace(customername, '', '***') as reemplazo

from

customers

--UPPER Y LOWER--

select upper('Microsoft SQL Server') as up, lower('Microsoft SQL Server') as low;

select customername, upper(customername) as mayuscula, lower(customername) as minuscula

from

customers 

--Predicado Like--

select customername

from

customers 

where 

customername like 'C%' --Búsqueda por la letra que empieza el texto--

select customername 

from 

customers 

where 

customername like '%a' --Búsqueda por la letra que termina el texto--

select customername

from

customers 

where 

upper(customername) like '%A%' --Búsqueda por la letra que contenga el texto (al inicio, al final, al medio)--

--FECHA Y HORA--

--GETDATE--

select now() --En sql server se usa la función getdate--

--GETUTCDATE--

select now() at time zone 'utc' --En sql server se usa la función GETUTCDATE--

--current timestamp--

select current_timestamp 

--current date--

select current_date 

--vista completa--

select now(), now() at time zone 'utc', current_timestamp, current_date

--CONVERSION DATOS TIPO FECHA Y HORA--

select *

from public.pg4e_meta