create or replace function zigzag_matrix(n) as table (
  with recursive cte as (
    select 1 as ix, 1 as i, 1 as j, 0 as ij
    union all
    select ix+1 as ix,
        if( (i + j) % 2 = 0,
            -- Even stripes
            if( i < n, i + 1, i),
            -- Odd stripes
            if( j < n, i - (i > 1)::INT, i + 1) ) as i,
        if( (i + j) % 2 == 0,
            -- Even stripes
            if( i < n, j - (j > 1)::INT, j + 1) ,
            -- Odd stripes
            if( j < n, j+1, j)) as j,
            ij + 1 as ij
     from cte
     where ix < n*n
   )
   select i, j, ij as value
   from cte
);

# The i-th row as a list
create or replace function ijTable2Row(A, m) as (
  select array_agg(value order by j)
  from query_table(A)
  where i = m
);

# Pretty-print the mxn matrix stored as an ij-table named A
create or replace function ijTable_pp(A,m,n) as table (
  select ijTable2Row(A,i) as row
  from range(1, m+1) t(i)
  order by i
);

# Create the zig-zag matrix as a table and pretty-print it
with zz as (from zigzag_matrix(5))
from ijTable_pp('zz', 5,5);